6 lug front diff to 8 lug

[TLoz]

Hi,
Interested in going from a 6 lug 4x4 front hub to a 8 lug 4x4 front hub. What's the estimated difficulty level 1-10? Parts availablity? I've got a 1977, 3/4 ton burb (2wd) going on a 1978 4x4 1/2 ton burb frame. Going to use the old diff and want to convert front over. My 16.5 tires and rims are like new. It's a stock 454 with 400 turbo, the newer frame has a 203 case that had a 400 bolted up to it. This should be an interesting winter project. Thanks in advance! Tom