OK, there are about 3-4 ways to tackle this problem....ONE...IF you have a hardtop you need to fit the windows to the hardtop and never move them again....
if you don't you have some more freedom....you can use the fudge factor to your advantage...in that adjusting the top height and fore/aft position on the lower inner two bolts behind the seats, along with the top/retainer requirements in the rear bow...you can then play around untill it's more or less 'OK'.....
now here is MY experience....you can play around all you freaking want,,...and use most any weatherstrip you want....IMO...the break between the two top of window sections in that weatherstripping, means water comes in at speed in the rain....
if you look at the aerodynamics of the water on the side windows, it flows UP in a line across the window untill it's over the top and in the car.....I have been playing on and off for a LONG time with the aero affects of that problem....and have made a very few small steps to attempt at solving it....without a whole lot of success.....
but don't worry, GM has the same problem with the C4, anyway on my '87 it did the same damn thing....I feel there is no reliable way to join two weatherstrips in a folding convertible top...over top of that side window, and have them seal weathertite...it just AINT a GONNA HAPPEN.....but yet, when on a traffic light, the leaking stops...i'ts a speed/wind related problem...aero dynamics....
so have fun.....Mind you, I have been playing on and off with this since '95 when I bought the car....mostly off of course, as I fergit to remember of the problem, untill the next rain storm....
GENE