When you dismantle it again to correct the globe valve position being before the safety valve, you might want to consider installing a union joint or three to ease future maintenance and modifications. ;c)
This is a good idea. I put one on the water pump which made removal very easy. Putting a union joint at the steam pipe on top of the boiler before the SV, and one near the end of the steam line would definately be a good thing. Measurements will be tricky to have it match up to what is current, though.