Scott,

If this 289 is already at .030 over, how much further will they go? I have a .060 289 in the Ranchero and it may be why it likes to run hotter than I'd like it to. I've read in multiple places you should have the 260/289 blocks checked for wall thickness as the bore increases as these were known to be a little on the thin side in some cases. Basically, everything I've read says not to assume it will be OK just because you can get the parts to do it. It was also suggested, if keeping the original block was important - and it was determined to be a little thin - you could also sleeve it to go back to zero.

http://www.enginebuildermag.com/2017...sonic-testing/

Also, a great deal of the heat made in the engine is from friction, not just combustion, and lot of that is with a flat tappet cam and lifters. Because I have issues with my 289 anyway, and because I'm not attached to it, when (and if) I ever get a garage to work in again I'm probably going to track down a roller motor and, if needed, rebuild it. You can convert the early blocks to use a roller cam, but it requires an offset cam to get the lobes down low enough, while maintaining lift, to get the roller lifter bits installed up-top.

Only passing on what I've read, since I have one. You're mileage may vary.