I heard about EBL flash and briefly looked into it. Can't say I know anyone using it, but if you're planning to stay below 15 psi it looks like it could work pretty well. I like the fact that it has an AC compressor input, purge cannister control, EGR and TCC control. I think the main reason I went with the Megasquirt was support for over 3 BAR maps but it would have been nice to have built in purge control and TCC as well.
The other thing you could consider is using
Code 59 which would require minimal changes to your existing setup. Mainly you would need to add in a 3 bar MAP sensor, but you also need prom burning software and something like a Romulator. The problem is these things cost as much as the EBL system, and Romulating with Code 59 creates occasional crashes during updates which totally sucks if you're sitting at a green light! LOL - been there, done that
One nice thing about the Megasquirt is the auto-tune feature. This has saved me a ton of time and works really well. Also you get data tracing in the 3D tables in the Megasquirt, while in Tuner Pro (that is used for EBL tuning) the data tracing is only in the 2D tables. Having it in the 3D tables makes it much easier to get the tune dialed in.
I like your plan.. keep it a 305, they respond very well to boost and you'll still get great mileage. All you will really need to change on the top side will be the injectors and a fuel pump upgrade. The bottom end is up to you, I'd keep the compression close to 9:1 and the stock cam would probably work fine. I'll let you know, I should have mine running on a completely stock 5.7 bottom end in a few weeks. I do plan to change the cam but I will stay very mild and let the boost do the power building. Just a good mild turbo grind is the plan.
You can figure on roughly doubling your horsepower for every 15 psi of boost. So if you build your bottom end to 250 hp and boost it to 15 psi, you will be at 450-500 hp.