Kurt,
The 26's will fly it well..
If you change it out to .75's I suspect that with the required
weight to install the 26's that it may not be much fun..
My best suggestion would be to send the motors to Ralph
Cunningham who is RCIGN1 on RCU and have him go thru
them if you thik they are not up to snuff... Seldom does
a gas engine go bad or wear out... Fuel cost is a TON
less..
The original Nosen 310 was listed as a .60 / .90
plane in the 60's.. On .90's it would fly ok and
thats about it.. These planes do fly VERY easy
and of course have a major pucker factor ...
Does it have retracts..? Flaps...?
Post a couple pics of it.. ok..
.