It's a 40 series motor, correct? (going by your other posts)
Perhaps i can help here with at least some of your questions.
Play in the pinion bearing (up/down) is fairly typical and normal for most of the "classics" that have NON - SEALED gearboxes. I must have stripped down around 30 of these by now , big boxes, small boxes, barge pusher boxes, and a whole host of 102 boxes, all with similar findings in most of them.
Charles's explanation of how to extract the drive shaft from the top of the pinion will work too, provided you have a decent vise. Just about every drive shaft i've seen or worked on will have filled up with crud inside them. Tricky to clean out, but i use a 8mm masonary drill bit that's 2 foot long!!! I got mine from B&Q a few years back. Attack it from both ends and eventually you'll blow the crap out of it. Soak in diesel for a few days, turning each end round so it gets a chance to soak in from both ends. Re-paint and it should go for quite a few years yet. Try a marine grease, not too much, up the inside of the tube when you re-assemble the shaft to the pinion. Wont do any harm to have a smear of grease on the outside of the shaft either, every little bit helps. Just my little tip here.
Pretty much all of what you've asked so far is nothing out of the ordinary. Heat is your best friend when working on old seagulls. I'd highly recommend you get yourself a good blowtorch unless you have one already. It helps a lot with most jobs whilst working on these old things. A big bucket filled with diesel fuel will act as a pre-soak for some of the bigger parts. Alternatively you could use WD40 or similar. (i buy mine in bulk ,12 cans at a time from the wholesaler)
As a general guide for compression in a 40 series, if you get around 100psi from it that's a good'un. They'll do ok with a bit less, but aim for 100.
Some have a bit more, some have a bit less (depending on wear)
Zinc primer is a good choice for rust prevention. I use this stuff a lot combined with either spray- on hammerite or the brush-on. They both work very well for me.
As you've pretty much taken all this apart i think it would be foolish not to have a look inside the waterjacket. You never can tell what lies inside. These corrode quite badly too and can often be the cause of poor waterflow which can eventually lead to bigger problems down the road. At least this way you can be certain that you wont have missed anything along the way.
Do the job right the first time around and it should last for years.
Help is always here if you get stuck
Jon
