Paxton on a 408?

That static compression may not be an issue. Whats the cranking compression? You may need a cam change with the SC. I'd call one of the shops that specialize in this. I know when I thought of running a procharger they told me I'd be fine with one, tuned properly of course. I have 10:1 static, 160cc.
160cc what? Your at 10-1 now with a Paxton type blower?
WOW!

What's the HP limit on a stock 360 block? 550, 600?
Depends on how long you want it to live. IIRC, Crackedback did a thread in this topic.
You are pushing your luck when you get over 600.
Even more so when your hopping on it a lot.