Nice job...looks like a really nice 350. Now that you got it at your place...jack it up and check all of your suspension bearings, wheel bearings, axle joints, and suspension arm pivot points. Im sure even as nice as it is...you will find some play somewhere. It wont be something that will EVER be totally tight everywhere...but it would be a good idea to check and grease the points...and asses any loose points that would become a safety issue...or tear up parts from being stuck/worn/loose. I would download a manual for reference and do a WOT compression test. Both before and after you change the straight finned head. Numbers for correct compression will be in there. Would not surprise me if you found a close to original bore size on that baby.
Take a look under it at the frame...check for bashes. Especially check for damage on the tubes that drop down in the front to guard the steering post and rods. They get hit quite frequently.
If all is good and safe...ride that girl...tell us how she goes.
WOW...two extra engines. Yeah man...this was a good purchase if you ask me. They look like they are pre-recall so may be worth doing some updating before being run. Also may be worth running the engine numbers through Honda to see if you got two updated spares or two that got removed before the buggies got sold at the dealer in 1985/1986.