78' 8-lug disc break swap to 67'?

[irishtrucker]

Looking to switch my 67' 1 ton drums to disc. I see there are some pretty hefty price tags for the 8-lug conversion kits ($900+).

I found three 1 ton pick ups (all 70's era) in the junkyard. I'm wondering if the disc breaks will bolt up seamlessly or is it better/smarter to buy the new kit??

Apologies if this is a rookie question - I'm still on the learning curve. Weekend Warrior.

Thanks in advance!