1984 VF500F surging / lack of top end power ???

Hi Guys, once again desperation is forcing me to the well of knowledge. I just bought an '84 500, the bike has 1200 original miles on it. It fortunately was stored correctly and is in very nice shape runs just as a guy would expect for its age. I have had the carbs cleaned and adjusted, oil and water changed. The bike when first started and/or driven for a short period of time shows no problems, as the weather was hotter and i rode farther I began to get a "surge" a "miss" ... something..... at normal highway speeds that was not evident in town or in lower gears. Once the surge started at speeds approaching 75mph the bike would not go any faster given any amount of throttle as if it were starving for fuel we changed the fuel filter, no change, air filter, no change. The mechanic found a bulletin VF500 #4 from august of 1985 addressing vent hose rerouting hot start problems / poor driveability at highway speeds due to internal venting of the carburetor float bowls. Among the recommended fixes are rerouting of the vent lines away from the center of the carbs [presumably to cooler air?] and replacement of a spring, jet needle and vacuum piston/diaphragm in the vacuum chamber as well as the new main jet and slow jets that are included with the "kit" This kit is apparently not available anymore and seemingly the problem was addressed on the '85s
I have 2 numbers on the Honda bulletin H/C 2082873 P/N 16020-MF2-004

Would anyone know anywhere I might find such parts, or better yet would anyone have dealt with a similar problem that wouldnt require another 400 dollar foray into the carbs.

Thanks in advance for any advice/tips anyone could offer, I really like this bike....the 30 miles i have spent on it ....and would like to put about 1000 more before the snow flies...and it was 32 degrees here yesterday morning so it coming
Trig