Yes you do need a "flap" (rustband) in your tyres.
Congrats on the good block. Are you getting it crack tested?
There are 3 7/16" pistons available for these blocks(not that I am recommending you do that) although 3 5/16" is pretty safe. (they are meaty in the bore walls) What I would suggest is a set of modern pistons, and a good quality modern set of rings. (along with the things Mike suggested) Don't be tempted by "cheap"
If you are able to locate a good mercury crank, that gives you a 4 inch stroke. The longer stroke is good for torque. As a preference the longer stroke is better than the bigger bore if you have a choice of one. A merc crank requires different pistons, so you have to sort out your plan first.
You need to read as much as you can.
I have just recently fired up my motor. 3 5/16 Ross pistons, with a std (3 3/4) crank. This gives me 258 cu.in.
Learn about ZDDP, What are good adjustable lifters, Cleaning out the block, Pertronix etc.+++
Enjoy the journey.
