nOOb I/O question 3.7 vs 3.0

[yodaddy]

I just purchased a 1978 V20 Cuddy without a motor. With a limited budget on this project, it's come down to 2 choices for powering the boat. Option #1 is a 1992 3.0/140hp previously owned and maintained by a Merc mechanic, and option #2 is a 1988 3.7/170 in very good condition. I've read plenty about the 3.7 problems, and would put on an aluminum head and external alternator before hitting the water if I were to go that route.

I'm a newbie here, and have been reading the forums (and not doing much else) for the past 2 weeks, and am very impressed by the depth of knowledge offered up by members. Any opinions as to the functionality of either of these motors over the other in a V20? Does a 3.0 140 have enough stones to push a V20 at reasonable speeds?

Thanks!