Cobrajeff pretty much summed it up. In short, budget and boosted dont belond in the same sentence unless you have the know how. Dont get me wrong here, i love car building too and ill encourage you till the end whatever route you decide, but the hard truth is forced induction is a total revamp of the car. If you have built other forced induced projects from the ground up, you could pull off a budget build. And we will all be here to help if you decide to go this route.
Now if you do go the route of building a budget engine for forced induction, buy the force induction system, buy all thats necessary for fuel upgrades, and then tune the car
If you decide to stay naturally aspirated and maybe later add boost, you could build the engine slightly upgraded over what stock is and it should be able to handle a few hundred horsepower more or just swap in a coyote package.