The main things you have to do for converting to 4 x 4, the front chasis legs need half moons cut into them to allow the clearance of the driveshafts. Also the tunnel needs replaced or modified to allow for the drop gear casing or transfer box! the rest more or less bolts on the diff ratios allow you to run the 7.5" rear diff along with the 4x4 front diff. but you will need the gearbox, front diff, front engine craddle, front drive shafts, both hubs then your front suspension needs changed there is a fair bit of work mate, my project car is just about finished and has been off the road now for 10 months but should be good when finished!

Nick

Go for it.