400 and purple cam

IMO bad combo.
4.34x3.38, 292* cam in at 104, 70* ICA
Static compression ratio of 8:1.
Effective stroke is 2.48 inches.
Your dynamic compression ratio is 6.09:1 .
Your dynamic cranking pressure is 111.49 PSI.
V/P (Volume to Pressure Index) is 97................................................97
This is slanty territory, how are you gonna deal with that? 3600TC and 3.91s? Ok then go for it. Just don't run it on the hiway; the total lack of energy efficiency and the 3500/3.91s will make driving more than 80 miles at a time, risky business and very expensive.

But if you boost the compression;
Static compression ratio of 10.8:1.
Effective stroke is 2.46 inches.
Your dynamic compression ratio is 8.13:1 .
Your dynamic cranking pressure is 163.26 PSI.
V/P (Volume to Pressure Index) is 143.............................................143

That's an improvement of 143/97= plus 47.4% That is a huge boost in low-rpm performance.
The 10.8 will show a huge boost in the midrange,and
The 292 will make the power at the top
Plus the 163 psi will make hiway travel possible cuz you no longer need the 3500/3.91s, but can run maybe a 2600TC and 3.23s, so 65=about 2500 with 28s and zero-slip.
I would run it with 3.23s and the stock TC until you figure out what you don't like about the stock TC and the 3.23s,lol.
Cuz 3.23s will get you 60mph at 6000...............at the top of first gear, and that means no shift. About the only gear faster on the street might be 3.55s, getting you 60=6600. But the difference is hardly worth the install. A 2800TC tho might be worth doing.

I don't know what the specs are on the factory 400 cam, but if it was a 252 cam, then here's what the stocker might look like;
Static compression ratio of 8:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 6.92:1 .
Your dynamic cranking pressure is 132.21 PSI.
V/P (Volume to Pressure Index)is....................................................134
134 is pretty good

But if you boosted the compression and left the 252 in there, this is what it might look like

Static compression ratio of 9.5:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 8.19:1 .
Your dynamic cranking pressure is 164.83 PSI.
V/P (Volume to Pressure Index) is167..............................................167

This is an improvement over stock of 167/134=plus 24.6%, again a huge boost in low-rpm performance, and the potential to make excellent fuel-economy. The power peak of the 252 might be down around 4400 and the shift rpm with a 2.45-1.45-1.00 trans might be around 5500; so 3.23s will get you 5500=55mph. I would just put some valve springs in it to safely pull 60 mph at 6000 and call it done. The stock TC would be fine with this.

A VP of 167 is pretty awesome, especially with such a tame cam.
You could easily re-configure and run a 268 cam with a bit more compression, and have a real performer. Might look like this;
Static compression ratio of 10:1.
Effective stroke is 2.70 inches.
Your dynamic compression ratio is 8.19:1 .
Your dynamic cranking pressure is 164.83 PSI.
V/P (Volume to Pressure Index) is 158.............................................158
So here you gave up some of that tire-frying bottom end, but moved the power peak up some 500 rpm, and moved the shift rpm up accordingly. Now you've got it all; bottom to top, a real strong streeter, with just a small for a BB 268 cam.
With this engine you might still get away with the stock TC and 3.23s. But with the extra 500rpm this combo will be quicker to 60 with 3.55s. Of course a 2800 would be gravy.

Remember that VP is just a tool that helps us predict thelow-rpm performance, that's all. On a streeter, low rpm perf is pretty important. So these are just comparisons that show how various combos might play out. Now go back and look at the first combo; the one with the VP of 97. Do you really want to take off like a slanty?
Here's one for RRR
292 cam in at 98
Static compression ratio of 8:1.
Effective stroke is 2.60 inches.
Your dynamic compression ratio is 6.38:1 .
Your dynamic cranking pressure is 118.67 PSI.
V/P (Volume to Pressure Index) is 110...........................................110
And compare that to a totally stock teener
Static compression ratio of 8.0:1.
Effective stroke is 2.86 inches.
Your dynamic compression ratio is 7.04:1 .
Your dynamic cranking pressure is 135.24 PSI.
V/P (Volume to Pressure Index) is 111............................................111