Rebuild 318 or go Crate

To get 300hp from a stock 318 2bbl you need some bolt ons. You don't need a full rebuild, and IMO if it ain't broke don't fix it when you're on a tight budget. If it's broke that's another matter...lol.

I also agree 100% with those who say it is virtually the same cost to rebuild a 360 vs a 318. 340s are a little more (less than $100 difference) mainly due to the piston costs. It's not "[I'm] down on the 318s". It's that economically in many cases if you need to source an engine you will get more value & reward from finding and rebuilding a 360 vs a 318 assuming both are available locally. If you can't get a 360 , the 318 in terms of output and feel is the same engine as a 340 once you rebuild it for performance.

Truth is there are a bunch of ways to get what you want. It's your car, your experience and tools, your downtime assuming daily driver status, and your money. So come up with your plan and either make sure you account for everything, or make sure you leave 10% of the total budget for stuff you forget and tools you don't have.