I can probably raise lid 1/2" or so, but not sure

Ive actually considered this, stock 502 mpi and I touch the underside according to the rash I can see.

tim,a 4150 carb can work great for your engines,even if you give up a little power you will still run good and be boating.on a street car engine i reciently did i tried a bunch of different carbs on the dyno,i ended up with a slight loss of power with a smaller carb[10 hp]but picked up about 15 lbs of torque in the 3 to 4 thousand rpm range,a good tradeoff for a street car imo.the main thing is to get the afr in the right place.

If these are 4-5" tall flame arresters, IMO, all you really need is 3". Any machine shop could cut down the height of the screens for $50-100. Another option we used with our 10" Gafrig FA's was to remove a few of the screens. The black Ultras would look great!
What our next hurdle to overcome? 

I think they are 4" but was also informed that a shallow arrestor hurts airflow into the carb, so 3" would be pushing it at that point thats IF they worked...

yea, I may still get stuck running my 800's just to get on the water, all depends on cash flow over next month or so.... so if thats the case I have time to look at solutions.... I started thread just to see what options are if I MUST use 4150 carbs.... the plan from day1 was to use Dominators..

The bottom of the Dominator FA is flat. Assuming you have the normal stepped flange on the bottom of your current 4150 flame arrestors, you would also pick up about a 1" when you replace the bottom plate on your existing FA's.

And after you pull it out Tim sell me your boat because it sure sounds like it is way to much work to bother with. ROTFLMAO

hahah you wont buy engines let alone my BOAT!!!

Ignorant question here. Can you not replace the surface area of the screen with width instead of height? "Bigger Oval" arrestors instead of the tall "stack" type? (Think dual arrestors, compared to single carb style). I see one issue with airflow having to travel a longer horizontal distance, and then down into the carb, versus a more direct flow with a taller style. Is it really that much difference?