righty tighty lefty loosy. If you have bolts left over say "oops" and keep going. j/k
Well if you have done it before is no big deal. If you have not you are in for a long week. With that said, if it's a b-series engine.... this is one of the simplest engines to learn with.
You need valve stem seals, intake gasket, exhaust gasket, head gasket, valve cover gasket, fuel pump gasket, carb gaskets (if you can afford it, put a Redline RGM or a Weber on there) rings, rod bearings, main bearings, maybe a new cam (Delta Cam in Tacoma WA makes performance cams as well as a few other places)
I've never rebuilt a 4 cylinder or any car/truck motor for that matter, but Mazdas are pretty easy to work on (unless it's a Mitsubishi-powered B2600 minus the i; those are a bitch) Just get a friend who's rebuilt stuff before to help you out, and if you have all the tools/equipment you'll need, and don't get sidetracked too often, you could get it done over a weekend once you have the block back from the machine shop.