273ci thoughts?

Your biggest challenge IMHO is that the stock replacement 318 pistons are all low compression. You need replacement pistons for most street/cruising use if you want a spunky engine for general street driving, and they all are lighter and so need the crank re-balanced. So just keep that factor in mind.

I am assuming this is more intended as a general cruising, sporty car for the road, but please correct that if I am wrong.