Whatever you choose I'll suggest you build it well so it can be effectively and pleasantly driven. Careful specs, careful machining and preferably quench and decent compression for both fun and fuel mileage on pump gas.

A well built 318, 360, stroker small block or big block or Hemi. What you want.

I went with a BB. 496B, Al heads, manifold and WP. Also Sanden AC compressor. It probably weighs less than the iron 318 I replaced. With suspension upgrades it handles pretty darn well. Pics are from an X country drive - >4000 miles in 9 days - and the road course.