Damper / Balancer - Correct for 350 ?

[PHOENIX]

I am replacing the damper/balancer on my crate 350 (the $1300 one) while doing other things.
I want one without the rubber outside, so I dont have to worry about slipping. I also want one that has the timing marks every 2 degrees for timing the advance. i have been looking at the streetdampr by fluid damper.
Here is a link: http://store.summitracing.com/defaul...tdampr&x=6&y=9

When I measure my damper with the pulleys on (so its not accurate) its just over 6" o.d. (maybe like 6-3/8"?). The streetdampr is 6-7/8" o.d..
Will this 6-7/8" o.d. damper work on my truck?
Will it hit my timing tab?
Do I want the internal balance or external balance?

If you know of another damper that meets my requirements above (no rubber outside with timing marks on damper) please provide me a link and price.

Thanks
Eddie