1971 factory 318

IMO the pistons will make a huge difference, otherwise you're lucky to get high 8.x compression with anything else. However, if you're looking for something temporary (whether a few months or a couple years) if it's a running engine, it's easy to do a cam and some headwork and have a fun engine. Just don't expect to beat anybody unless they have a stock 318 :) I did this with mine, and I'm happy to be able to cruise it, but long term I'll go with something faster.