i am thinking of going to a counter rotating alpha and have a freind with 2, 23 stainless merc props RH and LH would these be too big?? i have about 320hp 355's and running spenelli clever 21's with it beeing a little slow out of the hole but cruses nice. just wondering if the clever takes more power to turn over a standerd three blade any info would be great thanks >>>Greg

When the 260 Stingers were new they ran slightly better top end with the 23' standard ss 3 blade props than the 21's, however the diameter of the 23 pitch was slightly smaller than the 21 pitch.
With your extra hp over stock 5.7 260hp my guess is they will be close or slightly small. Borrow and lake test and pay attention to the Max RPM first and Max speed second. Make adjustments from there. You testing will be effected by the colder air this time of year and will slow in the summer.
Good Luck!

We have a bone stock 1985 260 and run Merc three blade cleavers. We have tried several other props and they seem to be the best all round for the this boat. I believe they are 21 pitch but I can verify if you need the info.
This boat is a twin right hand rotation, not counter rotating which would be a big improvement due to the torque over present which requires one drive trimmed slightly higher than the other to handle best.

You guys need to try the BALISTIC 23 from michigan prop comp.

They run top end like a 23 pitch and ecselerate like a 21 .
Real od shape. buton my sonic i had ,,gained in all directions.

I actually think they make up to 25 pitch,,so it would come out of the hole like a 23 and top end would be like a 25,,but still easy enuff to turn it because of the shape of the blades.

On the counterrotation ,,,i say YES ,,,lot better and spin out.
That means the counterrot. on the port and RH on the starbord.