If the oil level is high then I would wait until it has sat for awhile and crack the drain plug slowly until you get some drips....most likely it will be antifreeze.
Does this truck have orange extended run antifreeze? I had a 6.5 crack the block and I was running the orange stuff. My oil level did not go up noticeably but the antifreeze kept going down. The orange antifreeze was mixing with the oil enough and formed a black/grey goop that clung to the inside of the block. It was a MESS! but the oil draining out was normalish looking.
Will the coolant system hold a pressure test?
I would expect you have a leak some place due to the head gasket just being changed.
Did you use new bolts? What type of gaskets did you use?
1996 Chvy 3500 CCDWLB 6.5 Heathed, NO vac, marine injctrs, ARB bumper, BIG pipe, 3" lift, bright lights, bypass oil system.
1986 Chvy 6.2 M1009 blazer RAM AIR, Headers, Custom interior
2001 Chinook RV, V10 gas
1974 John Deere 1530 diesel tractor
1993 John Deere 455 Diesel lawn mower
1967 GTO, 1989 Honda Transalp
2009 VW Jetta TDI, flashed and piped, 6speed, fun car!
1998 6.5 suburban, stock, daughter's
1993 6.5 3500 CCSWLB GM8, Heathed, big exhaust, gauges, Son's
1984 6.2 ATS turbo 3500, SCDWLB - Son's
3 kids, 1 wife, 1 dog
Gunsmith, Tactics Instructor, Fabricator USMC 87-93 Semper Fi!