In the old days GM used a steel shim gasket, only about .015 thick and put them on the street for thousands of miles.
The one engine i ran .020 out was and alum blk. with steel rods and it was turning about 7500 rpm's thru the lights. I put 200/300 runs on the engine with no problems. As long as you have very little piston rock it should be o'k with .028 clearance.
JMO
Zip.