I have an old Craftsman table saw too! I inherited from my dad. It will work great as an alignment table! Place the bottom Bracket on the SE corner and there should be enough space to align your front triangle on the top using a surface gauge. That is one of the biggest headaches to solve when DIY. Ordinarily buying Paragon aluminum tube blocks and laying the out on a full scale drawing is the way to go (if you can't afford one of my fixtures) but you will be able to make the wood blocks as substitutes yourself. In fact wood blocks are your most needed and basic tool to hold your frame tubes when filing or brazing anyway so if you don't have any now, we can explain how they can be made.

I've actually thought a lot about how to make a simplified fixture based on mine just using materials bought at a hardware store and hand tools. However Americans - unlike the British - aren't inclined my direction. The majority have become more familiar with some kind of upright version. Don't count me in as one of the promoters of that style.