$600.00 should well and truly stop a pair of 40's in good nick.Dellortos are much cheaper due to the jetting and tuning problems,add another 150-200 bucks for 45's.A new redline manifold is about $300.00 with some grinding req'd to make it fit properly.The biggest hurdle is to find some one with old school weber experiance with a dyno inhouse and a large array of jets.

If you take a yet to be run in A15 with sidies along to get done properley expect it to be an overnighter and about $700-1000
My advice based on personal experiance in the sunny state...think hard and good luck

Cheers Bert