Spindles and brakes - AGAIN w a difference

HI - fixing up a 64 Barracuda. V8 with 9 inch drums all around.

I have switched the rear end to an 8.75 with big bolt pattern

I have a complete brand new 68 B-body 10 inch DRUM brake set up that id like to use.

I also have a set of the 73-76 A body upper control arms.

So looking at the spindles the B body spindle seems shorter than my 64 spindle? I thought that since both cars could use the 73-76 disc brake spindle that they could swap drum spindles ( you know if f=g and h=g than f should equal h logic)

Help - my 18 yr old will be driving it and i want it safe. and YES I will keep looking for disc brakes, but on a very tight budget and need it on the road asap.

Thanks

Dave

a friend just did that big drum swap on his scamp using his 69 road runner spindles and brakes with the big ball joint upper arms and it worked out great.