69 DT1 Carb help

Hi, new member here. I have been restoring old Hondas for 15 years. I am very active on the honda305.com forum, and have many 60s Hondas. I live in Nor Cal. I was recently given a 69 DT1 250. I got it running on starting fluid yesterday, and today I'm working on getting her running on petrol. I am in the process of rebuilding the carb with the keyster kit that came with the bike. I have a couple questions for the more knowledgable folks on the site. On the 305s, I avoid using most of the brass in the keyster kits, as I find the tolerances are not always as exact as the OEM parts. Is this true for the Yamaha kits as well? In the kit is a new needle jet, is this part replaceable in this carb, or is it a generic kit? On the rear of the carb are three holes, far left is capped. On my carb, the middle hole is clear, air blows through it, but the far right hole is pluggeg. Should air blow thorough this hole as well?

Thanks in advance, Davomoto