Last night I pulled the 350 motor out of my 69 firebird to have it rebuilt. I also purchased and rebuilt a period correct M21 Muncie transmission.

The 350 I have is rated @ 330hp after rebuild and some goodies I should be around 400hp. I would like some ideas on a mid-range clutch kit that will be good for daily driving and able to take some abuse every now and then.

Also I was looking at Ames Performance and the have a high flow water pump (Flow Kooler). I was wondering if anyone here has experience with this water pump or any thoughts on using it.

Yeah, that water pump will put you right up there at 400HP, no prob.(sorry but I couldn't resist)
It's really not as easy to make 400 horses out of a 350 as all the magazines and parts suppliers would like you to believe. But then again, all it takes is money(quite a bit of it actually).
I'm no help on the clutch other than to suggest that you buy a new one and don't go rebuilt. I never had any luck with the rebuilt ones.

I've just been through what you doing and asking. I'm rebuilding a 400 with right at 400HP. I went with the RAM premium clutch set. I purchased mine through NPD. I also asked about the water pump and about everyone that had used it saw not much difference. Seems most thought the cast iron prop water pump was just as good.

I was told that it would be 385-400hp by the shop, but I wont know for sure until the engine is broke in and dyno tested.
I am going from a 2 barrell set up with everthing stock and upgrading to a 4 barrell setup along with headers, cam, etc...

I am interested in the high flow water pump because it gets really hot here in the summer. Sitting in traffic on the way home from work I dont want to overheat the car.

originally that 2 bbl 350 motor (if all is stock currently) was rated at 265 hp. the 330 hp motors were all 400 4bbl.

http://thefirstgensite.com/html/enginecodes.htm

It's not the original motor for the car.

I really need help picking out a clutch and deciding if the flow kooler water pump is worth the extra money.

Not worth the extra. Spend the money on something else. And post the dyno sheet after you get it done.

RE Flo-Kooler: No better than a stock waterpump. Been there. Did that.

I'll sell you a flow kooler...

If you want to get a "high flow" water pump, get a smaller diameter pump pully...

...and research the divider plate clearance issue.

The AC water pump pulley is smaller and spins the pump faster, which will suck a bit more power.

Might not make that 400 HP but at least you'll know it was that dam power sucking pulley that did it.

Power sucker. Thats where my hp went!!!

Not sure I agree with that...but not important.