.030 over is not a big bore, thats not even 1mm over (.75 mm). Only bore your jugs "if" needed. Theres really no more gained power when you bore them out. If you want power, get your jugs ported and or get a 4mill long rod.
Some guys even run small bore pipes on larger motors, cubs ect ect, its what some builders like them to run, its all about set up.
If and when you "have to" go up to the next bore, just do that and go 1 more bore as needed. Bore/hone costs ranges from 30-60 per hole, depending.
Follow?