Have prop with a spun hub. What's involved in replacing it? We have access to about any type of press and tooling. Are there any special procedures?

What prop, what hub? Most Mercruiser are very straightforward, you use the stepped washer that is normally fitted to the rear of the prop and put it in the front and whack it, knocks it right out.

I haven't had much luck with re-hubbing props. Had 1 spin after putting in the new. They ended up welding a couple lines on the inside to try and give the rubber something to "bite"

Seriously consider buying a new prop with a replaceable hub.

Contact Spinelli Bros. at 315-594-2220.
They have a S.S. Weld in replacement.
Had mine done in May of this year and fits like a glove and fresh balance.

I have 500 ton press right over my shoulder here at work, but...
I have always taken mine to prop repair shop.
After seeing it done a few times, I will keep doing that too.
Not rocket science, but somebody that has been doing it for a living for a while compared to someone for the first time; I will leave it to the pros for the cost.