Been to Holland many times (grand-baby lives over there
). Seen quite a few muscle cars done very nicely. You'all have good resources like good Euro paints and such to do nice cars.
The thing I'd do is build a nice street motor that could do some duty on the drag strip a few weekends a year. Say 70% street and 30% strip.
The 990 heads have big runners so the mixture velocity is low at idle and around town speeds ( <3,500 say). That leads to fuel dropping out and other issues. But spinning a big motor at 3,500 rpm plus all the time will drink expensive Euro gas by the bucket - not good.
If you build the motor to match the heads it will be something like 6,500 redline and kind of limp at 2,500 where a lot of street use takes place. It will run, but not all that crisp and responsive around town. So you'll have to watch the traffic and the make sure you are building RPM so when that other car comes along side, you are well ready to leave
I hate to say this to you because of the costs involved, but I'd switch to smaller runner oval port aluminum heads and keep the cam and lifters you have if it proves to be decent one... That also means another intake manifold and the costs keep going up. Really sorry about that ... I'd be listing the 990's and the GM intake on Markplatz and in the racers forums. Someone will want them and pay well for them. Someone who wants 70% race and 30% street. You may even be able to swap for some nice 781's
Or, I'd work with Chris go get the best you can out of a street hyd-roll'er and those heads. It will be a compromise that might work OK, but ...
But I don't know where you live and what traffic conditions are like on most of your trips... I've been in some pretty long freeway line-ups getting into or around Rotterdam and such, it can be tough with a somewhat radical motor, rain soaked roads, and folks cutting in just when you get rolling ...
If most of your cursing to say the coast is at 3,000 RPM, that's where I'd focus the build. Make that the happy spot with max torque right around there, or slightly above. that way, if you want to pass a tractor hauling a trailer (they allow farm tractors on the highways in Holland), it's just a stab of the throttle away
It's all too easy to get dreamy eyed about building bad ass car and building in all sorts of big parts (heads and cams and carbs), when that is not what's needed. This is about building a package. That's why the folks are asking questions, they want more info about what you have now, how it works (or doesn't...) and where you want the build to go.
Stick around and keep the discussion going and we can get you a very decent build that will drive great. It just won't happen with one or two posts ...