[phoebeisis]

Cut open the oil filter-see if you see chunks or flecks of metal-same story when you drain oil-do it in clean container-look for metal flecks
If you do-maybe pull oil pan-look for obvious problem
No metal flecks could mean something relatively minor
Lotta metal flecks means rebuild or replace maybe
Luck
Charlie

 

[phoebeisis]

But like TB says-genuine GM Goodwrench rebuilds or new engines are CHEAP-
$2000 CURBSIDE for his 5.7 I think
My 1998 5.7 is just $2300 curbside-NEW GOODWRENCH-not a rebuild

 

[phoebeisis]

Looks good
Great it is running again-probably better-much better and stronger-than new
Weren't the 350's just 160-170 hp back in 1986?