My local shop charges about $8 a stick to swap tips/ reset pressures/ clean, etc. If you need a new tip, it's $60-65, though.
I'd just get some 1stGen 370 EDMs, esp if you are concerned about smoke and MPGs. 2ndGen piston bowls are different than 1stGens, which could give you smoke, as the 2ndGen tip isnt designed for the 1stGen bowl. Smell what I'm steppin in? I have been down the marine road too many times to put just any injector in the engine. If it isnt for a 1stGen design (i. e. the stock 6 hole, or 185 5 hole), I aint wasting my time or money.
Dan