Holley 390 and Offy Single quad intake questions

Hey Slant 6 Gurus,

I'm looking into a Holley 390 cfm 4bbl, and the Offenhauser single quad intake manifold, I just have a few questions I'd like to get answered if anyone has the knowledge,

So first of all, with the carb, I've heard of people using it on the Slant 6, but is it a bit too much for a stock slant 6? and how much fabrication would need to be done to get a working kickdown set up?

And with the manifold, the image looks like its fairly stock-ish, is it able to be used with the stock intake heating system or not possible at all?

Essentially I'd just like to make a bit more power without sacrificing drivability, if anyone has any other suggestions outside of the standard "throw a smallblock in there" I'm open

Thanks guys!