Chevrolet: 350 ci for boat, bolt mains, chevy motor

Question
I bought a new (older) boat, I have a chevy four bolt main on the side of the house, I am going to go through it and install same,  it has a 260 OMC now built in the 70's I believe.  I am going to install a roller cam.  I read on some site about chevy making Gen I, II, III, IV, LT1, LS and so one. Comp Cams says in thier catalog to make sure of the right type chevy motor, GEN I,II, III.... Q:  what is the difference between these and where can I go to get educated in this matter?

Answer
Rodney;
Hi; well I hope that the motor you have is for the salt water, also are the heads made for the boat or street,and will the water pump fit.. has the room. the 350 4 bolt mains is a good motor and should go great in the boat . I hope that you have the room to be adj. the valves if you are going to put in a solid lifter cam , I would use a hyd. cam with good anti pump up lifters and a good set of valve springs or a valve job. as far as looking up some stuff try the library and at the larger book stores the hot rod and other magazines will show and tell you a lot. and I think you should look into your oil filter and how you are going to change it on the boat as some must have the oil sucked out so think about a good set up with a filter for it. If I were you I would think heavy about a rolor cam in the boat on a car on the street yes but on the boat I myself would go with a nice hyd. cam and lifter set and h.d. valves etc. unless you are just going to yse it for raceing than go all the way but if you are going to go out fishing , skiing, and with some ladys , than I would go with a hyd. set up but a large cam , whaT pistons , or you going to keep the lower the same. also ( JC Whitney.com) has a lot to look at .  let me know how you do  ok p.s. what size / type boat