What's an MR drivetrain?
I didn't know Luminas and whatnot were available with m/t?
The FWD rationale is, the donor '59 has completely shot floors, trans, rear axle, etc.
The "other donor" '89 Le Sabre has good engine/trans/floors/etc. Drives like a dream, has astonishing power, and gets good fe.
Throw away that Chev X-frame (which I'm not all that fond of anyway as it makes servicing u-joints a rare treat. And, should lose a nice chunk of weight in the process) make sure the custom rockers are stout, stretch the Buick pan 11" (probably somewhere behind the driver's seat) and voila- unibody fwd '59 complete with cushy ride, good roll bars, good brakes, and air-ride suspension. Also the Chev driveshaft tunnel really puts a cramp on the interior- it would be grand to be rid of it. Heh heh flat floor could lead to lower seats could lead to top chop! Weight bias = probably not a whole lot different than the Buick. Total weight probably not a whole lot different either.