An LT1 that needs nothing mechanically for $400? Maybe. Maybe you get it home and take it down for fresh gaskets, etc. and find the short block needs the works, and one of the heads is cracked.
The idea of stuffing the 27 block w/a longer arm and pistons to match the CR and the stroke is a sound approach IMHO.
In that car, reusing the fuelies would look right, Vortecs will run better, your choice.
Using styling cues from that era on the engine (finned aluminum v-covers, a front-mounted oil fill tube, things like that) will offset any loss of "the look" from using different heads to some extent- but fuelies will be the best for popping the hood at the Steak & Shake.
If the intake has the U-shaped heat riser channel, be sure you use the right type of stainless steel clad gasket between the intake and carb.
Nice looking car, BTW. Good luck.