Make sure the crankcase blind mounting holes are clear and if using the cap screws, check that these to not bottom before clamping down the new pump. While it's off, treat the anti wet sump valve to a good dose of carb cleaner, preferably while the valve is pressed open. Surplus cleaner should be ejected, along with any carbonised oil and other deposits. Purists would remove the PRV and blow through the feed to the timing bush, which exits into the PRV cavity central hole.
I'd clean out the oil tank while the pump is off, blow through feed and return lines. Finally prime the oil gallery to the timing bush where you've just sprayed, prime the pump, allow it to drain a little before wiping the mating faces clear and assembling with the new gasket. Being an SRM product, all gasket holes should be in the right place and the right size.......
Swarfy.