I'm thinking about starting a projec to build a pair of BB engines so they are ready for installation this winter.

Was thinking about buying something "partially" completed so I could learn something and use some of the parts from existing engines.

I keep seing "crate" engines but are thye a good way to go to get good, solid, reliable pretty vanilla BB's?

Any suggestions on how to approach this long term project?

Again goals are to learn something, get experience, and get most bang for buck in process. Time isn't a big issue.

A 502 Short block crate engine is a good start. Try to find a marine version from some of these engine retailers. It will come with a 8 qt oil pan and a flywheel. It will cost about $200 more than GM. Do not buy a long block GM because thats when things start to change. The cam & valves are the biggest problems.

1-800-runsnew sells new 435HP/502 marine base engines for around $5200...
Long block with tin and balancer. Great place to start.
With a cam and a few other valve train component changes, you could build up some nice 500+HP engines...
Or leave them stock and have a warranty.