XR274HR-10 in 318

Are your '87 Roller stock flat top pistons .040 ths down in hole, like this '91stock 318 Roller that is pictured below ? That will be good for your compression.

Can go with the thin Mr Gasket G1121 head gasket too, with a compressed thickness of .028 ths. That will help too.

View attachment 1715548623

Yes, they sit down in the hole just like that.