Haven't posted on this site for a long time. Refuse to pay for info, anyway, the cheapest, easiest and a base adhesion that I would warrant, have the bare metal tins powder coated with a clear. The clear can then be scuffed and grafx layed on and your choice of bc/cc system. Works great.
HOK "Adhereto". I have 2 guns handy, one with Adherto and one with clear. One medium wet coat of Adhereto, then go over it immediaetly with a clear. I did a bike like this recently and it worked great! The first time I tried it I didn't use the Adhereto and the clear TOTALLY delaminated the next day!