6/71 all you need. 8/71 is fine but really not worth any extra money since between good blowers there is only a couple of pounds boost difference. Sometimes 8/71's are cheaper than 6/71 due to the nostalgia boys going through cores and more demand for the 6's. For lake use you want a loose blower anyway, especially on gas. Forget about 10, 12, or 14/71 blower. Offset mags required, special blower manifolds, not worth the effort for your purposes.