Ahh I guess I missed that you’re using the 10.25 in the rear, so you’ll go with the 8 lug wheel bolt pattern.
I don’t think running leaf springs in the front has any advantage and a lot of dis-advantages, I would go 3 or 4 link or traditional radius arm / trak bar and if you going with radius arms get and earlier D-60 that has a little more tube on the drivers side to attach the wedges to.
A D-60 hi-pinion only came on full size trucks which obviously are much longer than the E.B. and when you put it under an E.B. the pinion will pretty much point straight back at the rear axle, that’s why it’s best to re-orientate or clock the inner C’s that the knuckles attach to so you can get the correct pinion angle and keep the castor correct and then attach the C-bushing wedges, so you don’t wonder around on the pavement when driving it down the road, doing all this is fairly involved.
Prices vary on this mod from region to region and shop to shop, might call Dynatrak to get a base on what a shop might charge to do this, the shop that did mine gets approx. $500.00 maybe a little less, there was some horse trading between me and the shop so I don’t remember the exact amount, I had the bottom shaved and a locker and gears installed along with turning the C”s and installing the wedges, total was about $1500.00 and I’m also a friend of the shop.
At this point and for others thinking of doing this, I don’t think I would go with a D-60 if I did this again, it’s massive under there which creates oil pan & exhaust issues which can be solved with 5”s plus of lift, but that’s to high for my tastes, it wouldn’t be very much more as far as cost of obtaining a D-60 and converting it to 5 x 5.5 and setting it up with gears & locker and getting it set up to go into an E.B. to go with a 9” with D-60 outers on it, much less mass and fits a lot nicer under the front of an E.B.
Good luck, Francois.