Brake Master Cylinder - 5000

[pshenm at att.net]

So it looks like the brake master cylinder on my 5ktq sedan need to be replaced.  Apparently the 5000 avants had a 25mm bore instead of the standard 23mm on the sedans.  Anyone have any BTDT on fitting the Avant MC into a Sedan?  I know people have fitted the larger MC on these cars when upgrading to the ventilated rear brakes. I am concerned that the avant MC won't fit correctly to the current sedan reservoir, and I'd like to order it ASAP to get the 5k back on the road.

Mike Pshenishny
'87 5ktq
'87.5 CGT
'88 951