I have not rebuilt and Atomic 4, though they are very simple engines. If you have access to a machine shop, they can do the "tech work" for you. You can do the assembly and disassembly. I did this for an engine in my 1959 Lotus racecar, and it's been trouble free. Moyer marine will be happy to sell you parts and give you advice, too. The added benefit is that you become thoroughly familiar with the engine for the rest of its life. If you built it, you can fix it, huh?