help with gear ratio on mercruiser sterndrives

[Nova II]

I am looking at replacing outdrives and the ones I have found are alpha ones, but they are a lower numeric ratio. 1:30 and currently I have 1:50's. This is in a 26' boat with twin 260 merc v8's. Would these drives lug my engine or not and would my top be significatnly jeopardized? What would happen if I changed the ratio in the uppers to 1:65 or 1:84? I know it would fly, but could these ratios handle a v8. What kind of rpm's am I looking at. If I run the 1:30's , what pitch prop will give me a nice topend. Currently with the 1:50's, I run 52-55 on the gps with a 23 pitch cleaver @4500rpm wot. I really want to top out at around 70-75, and still have a good holeshot. Any info/ideas is appreciated. Thanks,Matt

[gonzo]

1.30 is usually for a HO big block. If you are running 23" props it may be possible to go down to 19" or so. To get that target speed you need to about double the HP. Twice the speed needs four times the power.

[Nova II]

Thanks for the info. Gonzo. What kind of top speed and holeshot would I get from the 19 pitch props with the 1:30 drives .Approximate my rpm's at wot or tell me how to figure this out. thanks,Matt