Calling all MK X /420G Experts

Lets build a nice, practical, go anywhere driver. Base car will be a 1963 MK X.
Electrics and all its limitations will be retained, ( Unless it makes A/C system impractical). Body and electrics are very good.
Which engine to retain? 3.8 or go with a 4.2 and related carburation?
Front Suspension- leaning to 420G with better steering box and brakes.
Rear suspension- leaning toward upgraded 420G with 3:31 ratio and better brakes. I understand there was a wheel design change for the larger brakes of the 420G? Unsure of what to do with Brake master.(XJ6?)
Fuel delivery- Upgrade submersible pumps to external?
A/C options- Have access to a trunk mounted Delair unit but are there better alternatives and which compressor/ condensor system to go with?
Cooling system improvements?
Any and all thoughts greatly appreciated.

  • with the fuel pumps, if they work, leave them, if busted, replace with out of tank units imo

  • The factory A/C is apparently good, as the evaporator is big as a Mack Truck, my car was originally non A/C, and I am fitting parts, long story

  • No enhancements to the cooling system should be needed, unless your radiator is not partially blocked

one “bad” thing…3.8 have a solid steel fan without a Viscous clutch, so chews a lot of power at high RPM

I’d definitely use the 4.2 engine,more torque, better engine response. Also go with XJ6 15" wheels, more tire choice as well as after market wheel choices (Chev same bolt pattern).

Mark X BW transmission is problematic. I would go with a later 420G unit or a T5.

If you go with a T5, keep the rear end and the 3.55 gears. Watch out for drive shaft diameter half shafts. You may experience them hitting the shocks with modern wide radial tires.

Burman power steering box may not like the modern tires too.