Holley Street Avenger 670cfm to big for 318cui?
no it is fine , i ran an 850 tq on my 318 back in the day ran real well , that 670 should do well on a 318 . Street demons are also good
And with a manual trans, you will be able to tip in the secondaries much earlier than with a stock-stall auto, and in the process get some tire-frying fun.
I will disagree with the other opinions & suggest you swap the Holley for an Edel AVS2 carb.
I agree with most of what you say except OP is in Germany, so it's not like in the old days when you could buy a new carb for the price of a couple of tanks of gas.
i have bought some new parts for my stock 1969 Plymouth Barracuda, 318 small block with 4 speed manual.
The most-fun combination I have had, for a stock smogger-318engine in a 68 Barracuda, was a SMALL-PORT intake with a Thermoquad, which is a spreadbore Air-valve Secondary carb; and with some rear gears to make a starter gear in the range of 9.5/11 to 1..If I had it to do again, I might choose, a small mechanical secondary style of carb. But IDK, I love that TQ roar.
But that does not mean that the induction combo you have purchased will be significantly less fun. You just gotta tune it up real sharp. And not having had the small-port/small-carb combo, you will never know what you, IMO, are missing.
I assume you already have headers and dual exhaust, cuz the duals at least, shoulddabin your first investment.
I do not believe there is any such thing as too big a pipe size; With headers, mine was absolutely fine with full-length dual 3s; but I'm sure that is serious overkill........ I already had the pipes for my 360,lol.
