Need a little guidance from the gurus

I feel I need to clarify a little:

I was hoping to get a reliable and fun summer driver for relatively cheap (was hoping to stay below $5kCAN which is like $500US right now).

I am not afraid of work/modifications although I am fairly green when it comes to automotive mods but you don't learn until you try. Trying to find a way to get everything I need/want and not have to re-do too much later.

Regardless of the route I go, this is where I am at:

-I need a tranny built 904/BB727 (thinking probably $1k)
-Want/need headers ($500)
-Engine upgrades (carb/intake/cam) ($1500)*can hold off on this until later
-Misc (motor mounts/flexplate/other)($1000)
-Rear end ($1500)(seems to be the cost whether I find the right housing and rebuild or find one that doesn't need to be rebuilt but modified ie ford 8.8 or a dana 60)

My thought process here (usually out to lunch) is that if I go the motorhome route (plenty of them for sale around $1000 with less than 40,000kms), I get more HP out of a stock motor (can use the engine upgrade money towards other things like brakes which is probably a good idea regardless of SB/BB). I can do the top end stuff to the engine down the road

Obviously this doesnt factor any of my time/labour and pulling motors from motorhomes can be a pain from what I hear, but like I said I am not afraid of the labour. I like the idea of the 360mag, which I think will be relatively the same cost for everything behind it until I start to warm up the 440 being that I will have already taken care of the tranny/rear end.

My apologies for this thread being all over the place, but am I way out in left field here?