Does anybody know what the off-white paint color is called for the OTA?
The tubes were gelcoated, not painted, and it was done prior to forming on the mandrel. Judging by the cracking I see on these, the shop that made these was thinning their gelcoat with acetone instead of styrene monomer. Cheaper but doesn't allow full polymerization and excessive cracking and shrinkage is the result.
You will have to have an automotive paint shop color match the old gelcoat. Modern whites are much brighter than they were 50 years ago.