Offshoreonly.com - Finalizing blower..need help with sizing

So I got my engine back from the builder finally and my plans are coming to reality and its time within the next few days to decide on a blower....engine is a 454 bored .060 dart iron eagle heads custom comp cam(very similar to 525 cam) JE blower pistons came out to 8.2:1 compression eagle forged rods....I had a 256 weiand for this build but have since realized its not worth my time to put that blower on knowing I'm gonna take it right back off next year soooo...I found some extra cash and am going either 6-71 or 8-71 from Dyers...

I have a 6-71 core in my basement and with cost of conversion, drive kit, intake, and top hat I'm right in the 2700 range to have a complete 6-71 kit

They told me they would give me 300 for the blower core if I don't convert it so that puts the 8-71 complete kit at 3050

So my question...what blower would benefit my build better...this will never be a high boost race deal just an aggressive and mostly reliable pleasure boat with some poker runs in her future

I know bigger is always better in some cases but if I'm in the 5-7 lb boost range on either of these blowers is heat really and issue??

I'm running twin 750's on whichever blower I decide to get and I also have CMI headers....boat is a 97 Nordic heat and my goal for this deal is to run consistent and reliable 80 mph...for a baseline...it ran 75 in cool weather before the rebuild with a wore out 525 sc so I'm basically looking to gain 5 mph minimum and not beat the snot out of everything to do it....will going from 6 to 8-71 in this case make much of a difference??

thanks