I have considered boosting the 305. The only thing is we have a 10.5.1 compression. Which is way to high for boost. So I’d have to lower it to at least 9:0:1 or 8:5:1 preferably
Just change the heads out for some 76cc large chamber 350 heads, which are the most common SBC items in the world practically. It will drop you in the area of 2 full points of compression.
these are typically found on any 1972-1985 car or truck 350. almost dime a dozen, you can likely find a decent used set on Craigslist or similar, or check with your local machine shop, they will often have rebuilt pairs of these sitting on the shelf, from customers who never return to pick them up, tyhat you can get for cheap.
That 350 a family member is letting you have most likely has a set of these sitting on it right now.
And they are pretty much worthless for any real performance work on the 350 when you build that later, so it's a win-win.
I'd use the 1.94" intake valve size versions if you can finds them, With a turbo blowing through them it will minumize the shrouding effect the small 305 bore will have with the bigger 1.94" intake valve, which is usually considered a problem on naturally aspirated 305 builds, but the turbo cancels that effect.