3.0 or 4.3 mercruiser ?

[Tarpun]

I,ve been thinking about replacing my 1972 Seafari's original 3.0 pre-alpha engine and drive with a more current model. I have come across complete later model 4.3 with Alpha 2 drive. It's a more current 4.3 with balancer. My original plan was to stick with the 3.0 for good economy but since the avail. V6 has me thinking. I know it weighs more and will burn more fuel but it will be less stressed and allow a faster cruise. I was always under the impression the 3.0 was a good unit but a couple folks have said they have gasket and manifold problems and that 4.3 is better in that way, also that the 3.0 is too little power for the Seafari. I don't plan on taking divers and gear or generally using it with more than 2 or persons total. So how about some learned opinions from the forum. I would love to hear off hands on experience. I did a site search and did get a little info. How about it ? Thanks in advance. Dave