"B" body drivetrain into "A" body

After changing to the A body engine mounts and exhaust manifolds, I finally have been able to install my 273 and 904 from my '65 Coronet into my '65 Dart. I had to modify the crossmember in order to accept the trans mount and while I was at it, I also modified it to accept dual exhaust. It appears that the A body 904 must have a different tailshaft because I will never be able to hook up the speedo cable because of chassis interference, and the driveshaft is going to need drastic shortening.
Is there a plug available to fill the speedometer hole?
My B body downshift linkage won't fit the tight engine bay either. Anybody have any kuck with the cable operated downshift linkages available?
I was also able to install all of my spare Coronet front brake setup, giving me much better brakes. All I had to purchase was Upper A arms for a late disk brake A body and everything including upper and lower balljoints bolted on.
After Moser did their thing I was also able to install an 8 3/4 from the Coronet.