Twin Turbo 383 questions

I am new to the Turbo thingy and have been searching the internet to determine what turbo's to choose. Most of the drag cars down here are going turbo and WoW, they are getting seriously fast! Obviously Garrett is the instant choice but I was struck by a damn lay-off!
I have read many comments on the Masterpower brand and looks like this may work for starters. Only one concern is that I cannot find info stating that they are "ballbearing" type. I think that with these things spinning 10's of thousands of rpm's that they really need to be bearing type.
I found some so-called 70mm's on ebay for $188 but I am aware of "you get what you pay for" thingy
I have decided to use a Blower camshaft and work from there. I am converting my 850 Holley DP to a Blow-thru per an article from "turboforums". This will get me going in the direction I am aiming for.
I have a few questions about the exhaust turbine size. Seems from what I have read that the .68 is gonna work but something was said about back pressure. I would think that the wastegate would correct this as well as the mid-to-high rmp shutter. Is the smaller size gonna spool up quicker? Or should I go with the .98?

Come on, Bang heads with me!