a simple compression test will tell you how the top-end is doing....but it never hurts to pull off the cylinder a couple/few times a year, just to verify the cylinder walls are good, and there's no cracks in any intake/exhaust bridges...if the 65 even has bridges.
you can check the crank tolerances when the cylinder's off easy enough...just be sure to get a service manual, so you know what the tolerances are.
as for the tranny, just keep that oil clean, change it often, and it should last you a couple seasons easy, providing you replaced all the bearings and seals, with this fresh rebuild you said you just did.