Your 460 is a little different than most 88 460s. Ford introduced EFI in 88 for most of their 460s. Your engine is a carry over with a carburetor. Use an intake manifold gasket for a 87 with valley pan. The carbed 460s have an exhaust passage through the intake manifold. The EFI 460s does not.
The china wall gaskets are known for leaking oil on Ford V8. The intake gasket coolant passage is usually very durable and not known for leaking coolant into the oil. With the over heating issue, I would pull the heads when the intake manifold was removed.
A leak down test would be more effective than a compression test for finding a head gasket coolant leak.
Richard
95 Bounder 460
95 Bounder 32H F53 460
2013 CRV Toad
2 Segways in Toad
First brake job
1941 Hudson