Whoa. there are a lot of people on here so get lots of opinions and here is mine. If you get aftermarket heads then you are not staying with a numbers matching car and engine! If your willing to change the heads then there is no point in using that 305. My suggestion is to save yourself a lot of work, aggravations and $$$. Buy a crate engine, it has a warranty. With 35K you can get a great fun engine for your car. Put the 305 in the garage. as you learn if you so choose to you can buld that motor later back to completely stock if your keeping the car original for classic purposes. If you want the experience of building and engine then go buy a used core 350 from a yard, and build a nice 383 stroked motor that all torque so that you couldnt wipe the smile off your face. To build a 305 and keep it all orignal I understand. A 305 all stock in your car is not fun to drive considering ever 4 cylinder rice burner is gonna beat you up on the street. To build a 305 for performance makles it not original and as most on here would agree a 350 or 400 small block is a much better beginning platform. JMO. Whatever you do dont rush into anything; read and listen to experienced people as much as you can; most guys building their first motors end up with costly mistakes, and motors they are not happy with. Good luck in whatever you choose.