Advice on throttle conversion.
 

I have the TBs off of '77 and a '81 924s. One is going back into the '77. Which one should I use?

Both are dual bore. The older, origional one has measurements om 32.5mm and 40mm. The new one measures 35mm and 45mm. Also the older one has a small (~3mm) hole in the smaller butterfly.

Are they interchangable? Should I go with the one with the bigger bore? Will the little hole matter? Also, the million dollar question, will the bigger one give me better HP. Any feedback would be great. Thanks guys!

I have heard that this was actually a worth while upgrade. No personal experience to speak of though...

I really want to pick up an early 924 to play with but can never find one at the right price. Anyway, good luck.
Ahmet