Good plan,unfortunatly in Oz you can get any H150 ratio you like...as long as it's a 3.9
I'd make the change anyway,i use a 3.9 H150 in my H145 housing
with a mild A14 up front in competition without issues.The only way to get a shorter final drive is to put an H165(ute) under the back or get a ratio set made for big bucks.

I'm going to pick up a 1980 210 w/a 5 spd, A14 & H150 rear end. I got the car for free & all I wanted was the 5 sp. but I was thinking about using the H150 pumpkin in the 1200 rearend housing if I could get a gear ration of 4.11, is that a common setup in AU & If so would someone have one available they dont need/want to sell?

My concern is the A15 I built for the coupe might ruin the H145 4.365 center I have & that'd be a shame, seems like the smart money's on putting something stronger in there.

Thoughts??