S-Chassis.com - parts selection trouble

Hi everyone. Well, now is the time to start ordering parts for the sr20 project. I just ordered my turbonetics t3/t4 turbo, and now its time to order the supporting modifications. I am thinking of getting a tial 38mm external wastegate, but I don't know what spring tension I should get, I was thinking somewhere along the lines of maybe a 0.5 bar? What do you think? Also, what injector size should i run, would 740cc be sufficient? And I have seen flage kits on ebay for the T3/T4 turbo, I was wondering if I would need them, and if gaskets will be included with my turbo header, hotpipe and intercooler kit. Finally, I am also debating which guages I should buy, I know for sure i am getting an A/F guage with wide band O2 sensor, and a boost guage, and maybe exhaust temp???? Please give me your input. OH, and I almost forgot, I am trying to fine some stainless steel valves and new rockers for my head, doing a complete rebuild and 5 angle valve job on that also, so if anyone knows where i could purchase thse items, please tell me. Thanks. -Derek