I've got a PR410hlf and it is a monster sounding cab. The troubles I find with it are:
1. It is VERY heavy. Make sure you're willing to deal with that or you'll be cursing yourself for not debating how much fun 126 lbs is to move around.
2. It's very large. I can fit many 410s in the trunk of my car, this one won't go. It is also a lot of trouble to get into the back seat. Very deep. But that's why it sounds so huge.
3. IMO the more power you throw at this cab the better. I'm currently using an SVT3Pro with it and found that 450 watts is pretty good, but, recently had the opportunity to try an SVT4Pro and the higher wattage made the cab sing.
The last thing (and this isn't a detriment, but considering you've got an old school tube amp...) the PR410 is a very modern sounding cab. In fact, I'd go so far as to say it's almost not an "Ampeg sound" in any way. The lows are prominent and the highs are clear and present.
In the end, if you can deal with the first two things up top, then plug your amp in and see what you think of the sound. It is a GREAT sounding cab.
Phil Lesh Appreciation Society #26
Gordo Club #9