4 bbl intake 273

What gears are you running? Automatic? and stall?
The 4bbl by itself won't do much until it flows more than the 2bbl.
A 2bble is usually good to, lessee;
(200ish-cfm x 3450)/273=2500rpm; so says the math.
Lessee;
If you had small 14s(25.5 tall) and 2.73 gears and a 904, that might be 27mph.
If you had 3.55s, it might be 20.5mph.
If you had 3.91s it might be 18.5mph.
If you need more jog below this, your 273 will want more TC first.

On my 73-318 stock long block,I loved a 2800 and 3.55s......Then the TQ moan.
Hang-on, I ran the A998 behind that for a starter gear of 2.74x3.55=9.73. To match that performance,you would need 3.91s. Oh wait I have at least 400 pounds on you, so back to the 3.55s.
IMO, it would be better to put the money into the TC at this point.Even keeping the 2bbl.And with the torque-slope of the stock longblock, IMO a 2400 is not enough;but, I don't know your driving style or intended use. I just know I loved the 2800.
And, I would up the gears a minimum of 20%, to a maximum of 3.55s,for a streeter that occasionally hits the highway.
If you did these both at the same time, you better take it easy the first time you floor it! I would make sure the LSD is working, and HANG-ON!