Don't use the 305H. It is a very lazy cam designed in the late 80's. I know that sounds short and silly, but that is VERY far from being a good choice on damn near any engine that does more than cruise the boulevard sounding good. If you can stand some maintenence, I would go with a solid cam for higher ramp rates, or at the very least, use a Extreme Energy hydraulic/Modern ramp design, and also consider a 1.8 rocker. The generally used measurement for dynamic compression is based on degrees of valve opening to to degrees of crankshaft rotation. I.E. a different way to look at your static compression ratio. What I in my own weird way consider dynamic compression is actual cylinder pressure under running conditions. Meaning that every engine combination has a different VE (Volumetric Efficiency) curve. An engine with both lower static as well as the standardized measurement for dynamic compression can easily see more cylinder pressure than one that is higher on both counts if the package is correct. If the engine is designed to fill the cylinders via camshaft and cylinder head selection, static and dynamic numbers are pointless. The choice of the peanut port head makes sence somewhat, but a Edelbrock performer head would actually perform much better, not to mention weigh a TON less.
As for the 4/7 swap...I use them pretty regular. They tend to idle better, and in some application have better throttle response, as well as more power across the spectrum. But this is very minimal to nill in lower HP applications. Take it from someone who was skeptical of them, and tested quite a few...From my experience. The main plus...Easier on #4 main bearing, and generally a more "crisp" engine.
I know I probably just made another mess with a half-assed reply, but I also hope I put some brains to work for the guys on a budget who like to build their own stuff. And if all else fails....DO NOT use the internet for advice. Call the cam company of your choice. INSIST on someone with airboat experience, and have ALL your DETAILS ready...And then see what they have to say. Otherwise, spend the money and get an engine that performs in an airboat from someone who knows what they're talking about.
Appologies in advance for any typos or lack of 411...I just got home, read the post and two-finger typed off the top of my head. LOL
Forgot to mention....I've been drinking also. I tend to get creative under these circumstances, but also miss some details along the way. So, take that as my disclaimer