I'm about to do this on my 240 but don't get me wrong, theres nothing wrong with my SUs and I will be able or atleast should be able to tell a diff. I honestly beleive that the 4bbl. is going to be better.
Next con is same issue as with tripple webers: you're gonna have to play jet switcheroo to get 'er running right at a reasonably wide range of engine regimes. The only really good way to do this is with a dyno and an emmissions analyzer so that you can see what's up as you try various jets. This can get pricey.
With SUs you're gonna be pretty good to go with stock or SN needles regardless of engine displacement and cam variations.
since I have been dinking arround with engines , started about 45 years ago I am an old hot rodder engine builder , mutiple carberation has always gone hand in hand with performance untill injection came on the scene in the 59 corvette. Any way a 4 barrel or duel 4 barrels worked great on a v-8 because of the short distance from the carb to the intake. With an inline engine multi. carbs. spread the source of fuel closer to the intake of each cylinder. Thats why multi-port injection works so much better than throttle body injection. Throttle body injection is just one little step up from carberation. The advantage of the SUs is the simplicity of the unit and its high performance . Most any one can learn how to work on them and with the vido available why change. The grus that have access to dinos say that the SUs provide all the carberation that the Zengine can use reguardless of weather its a L24 or a blown out stroker. If you want to spend $$ go ahead. thats my 2 cents Gary Portland
I know that some of what you say might be right to some people but I'm not one of them,I just installed a 4 bbl. on my 240 and it run great,more responsive, revs. way faster and starts without a choke, this is just my opinion,however it is one of wisdom. Fuel injection was 1 introduced by GM on the 57 two door hardtop sedans before the vette.