17 and in need for power!!
Thank you everybody for the comments. The only thing with saving the money for the 340 is we have enough parts to build 2 or 3 340s. So parts aren't an issue exactly. I was looking into making my car a bit more peppy rather than a slow cruise. I don't plan on racing due to cops everywhere in this city but I would like to hit 0-60 is a little less than 18 seconds haha.
I would start by giving the engine a good evaluation and going over. Run a compression and leakdown check. Adjust the valves. If not recent, change plugs, wires, cap, rotor, and points if it still uses them. Check the distributor for sticky advance. Play with the timing a bit.
You might be able to gain a bit "in the meantime."
Example. Let's say the car has an 8 1/4 rear and you are going to keep that. You could drop to a bit lower gear and put a sure grip (or after market limited slip such as trac lock) and IF you are going to stay with a 904 automatic or 4 speed, you can keep the rear end and drive shaft once you get the 340 in there. Switching to a 727 automatic would require a new driveshaft, or at least shorten yours with a new front yoke
Decide what to do about brakes / suspension. Are you going to stay with the small pattern wheels? If so, investigate the aftermarket disc brake conversions. Find some heavier T bars and add a front sway bar. Upgrade the shocks for good handling. Go through and rebuild the front suspension. Get it aligned. You can plan what wheels and tires you will use if you are going to change. Handling is ALWAYS an issue for these cars, and the slant equipped cars were not known for being "equipped."
In other words if you plan carefully you can do a lot of work "on weekends" before you get to the engine swap.