Swapping the inline for a bbc

[Radford46]

Hello, pretty much a newcomer/watcher here but bought a 68 stepside a few months ago. I'm in the process of getting bodywork done and gathering parts for a 4/6 drop and a bbc/ 4spd conversion.
Couple of questions...will the bbc fit using the stock heater core shroud? Doesn't look possible to me. If not what is the alternative as far as a different shroud? Also, this truck is about as basic as they come! Has 1 option on the list in the glovebox,heavy duty clutch. It has a factory drilled hole in the left front fender,is it for an antennae? Radio delete, so kind of odd. Thanks, Kerry