You really need to state what you intend to do with this car.
Sure I run my cars down a dragstrip occasionally but the percentage of the total miles is far less than 1%.
My observations...
Adding power brakes wasn't necessary, adds weight and introduces more potential reliability issues.
The Mopar torsion bar suspensions were superior to the Ford and GM stuff. Upgrade the t-bar diameter, etc. There's a reason those others get replaced because of bad geometry and inferior parts.
Of your engine options, the G3 Hemi is the most complex and expensive on your list.
A good 904 is fine with a small block and less parasitic than a 727.
Check out your 273 and if not needing a complete rebuild, run it for awhile with a good tune. After a year or so, you'll know if you want more power.
A later 5.2 or 5.9 Magnum is easy and pretty cheap to do. They were made with non electronic OD trannies for a few years in trucks and vans. 3.91 rear with OD should do it.
Radical engines sound good but is the price of gas going to go down?
