Never done that job in a Morgan, only in an MGBV8, but some of those bolts are quite long, so I suspect the radiator will be in the way. The bolts should have special sealant applied to the threads before installation because they sit in the water jacket. BL recommended a sealant which also doubled as an adhesive...............
Before loosening I would try a bit of localised heat from a blowlamp on the bolt head, then tap the spanner with a hammer, because the shock approach has a better chance than soft torque. It's a matter of feel and luck in the end. The pump I took off was 16 years old, and all the bolts came out OK, but I didn't expect that.
