'89 K1500 engine replacement help

[custom1970]

New to this forum, but not to the site. My son has a 89 short bed 4x4. The old trans and 350 were worn out, so he wanted to replace both at same time. We found a rebuilt '75 4 bolt 350 with a turbo 350. After some trans and engine bracket mods we finally got everything installed last weekend. Went to try and start and the starter is not getting power.
Wanting to know if there's any safety or computer deals that needs to be deleted or bypassed? Acts like neutral safety, but it's on column so shouldn't be a factor.
Have power to key, coil, fuel pump.... Just not to starter.
My next step is to re check starter, but hoping we missed something else. There's tons of unhooked wires when you go from new school engine to old school....
Any help much appreciated.., thanks