Checking 904 Endplay

Nearly ready to finish up my 1st 904 rebuild but have a question or two about measuring the input shaft endplay. Our resident tranny gurus all suggest standing the tranny on the tailshaft and then measuring the input shaft endplay. My question is does the tailshaft housing need to be bolted up with the big bearing and C clip in place before the measuring is done?

Regarding that giant C clip, any tips for installing it? Taking it off wasn't a problem, but putting it back looks tricky. Do you put in place (sort of) in the housing first, then slide the housing up to the bearing and then spread it? I'm sure there's a trick. Please share. Thanks fellas.