Don't biuld a 9''. they are weak...................but drag guys and race guys run 1000+ HP threw them.........yep.... and they spend a shit ton of money on them. You have to spend
$500 dollars right off the bat to get it to Dana 60 strength.
then you have to biuld the inside. then you need shafts.
9" have their place in comp budggies for weight and clearence but for the average joe that is going to beat his junk. I think your putting in a weak link that will continually cost money unless you drop alot of money in it.
High 9's in the rear are not what they are cracked up to be, in the front yes, rear apps I don't care what they say, its on the weak side gear and it will break.
you can weld your 60 spindles on to the 9inch housing to get your 8 lug that is the easiest way.
someone suggested bolting on a front spindle, that works too after welding on a flange, but its expensive to use front pieces, no one is giving away front spindles and hubs. and then you will need to run a double splined shaft and slug. this is how alot of guys were running double splined shafts in there rear 60's. do to expense is why we came out with these.