My engine has 110,000 miles and blew the head gasket. I'd like to remove the pistons to replace with standard rings and standard rod bearing. Can I do this while the engine block is still mounted?

Yes, but it would be a lot easier with the block out of the car.

If you're planning to change the bearings & re-ring the pistons, you might as well rebuild the engine. If you're not concerned with matching numbers you could drop in another engine. I think Jasper Engines has rebuilt engines for a reasonable price.

If you don't have a "cherry picker" or "engine hoist" check your local yellow pages under "tool rental" I rented one for $25.00. Buy an engine stand for $40.00 and rebuild that engine with ease. Like previously mentioned you can do it with the block still in the car but the crank is very heavy. Heavier than a V-8. And to remove the oil pan you pretty much have to raise the engine off the motor mounts. So in the long run you will be much happier if you pulled the block.

and before you start throwing "standard" bearings in it, you might want to make sure that there are no problems with the crankshaft that require machine work and over/under size bearings. Heck, if you're going to rebuild it, why not do it the right way and have the block & crankshaft hot tanked and fully serviced by a competant machine shop. No use in doing a half-assed rebuild now, and another one in a couple years.