Hi Eric

Say ,what sq ft is the typical sq top H 20 main ,
and mast height also?

One really nice retrofit for the H-20 would be a C F replacement for the comptip ,weighing half evan though longer ,with a sq top main ,-great mid pole spin snuffer package with 270 or 300 spin ,-
more technical ,-reseat the crossbeams in an expoxy mix
{Wax paper}for release ,-but 4 or 6 degrees of cant added ,
simple to do though bolt reallign tougher .
Then add a little fairing stern extention -foam core epoxy to lengthen it to a full 20 .
If refinish of hulls is required ,take it in and have all excess fg ground out and hulls lightened by 25 lbs or so then repainted with colorfull {F-20 } graphics and team boat name ,--whew .
sorry ,got carried away !

Think you,ll end up with a very high spin pole , suggest dropping a lead wire down with holder from the bridals .
Would add a spin pole bridal wire and strut support and then use 2 sets of pole wires --one intermediate and one to the ends to transfer some loads from the jib bridle wire location attachment .
Some N 6/0s drilled a hole thru both sides of the hulls near the bow tips for spin pole wires or non stretch line but they have the forward foil the spin pole attaches to transfer some of the spin loads , which are significant at times .
Not sure about the bow drilling ,-best to check with other H-20 spin catsailors if that is your preference,