Number one, I think its a good deal, and a great starting point. Number two, just because other guys bad mouth 318's because their own experience with them is in 7,000 pound four door sedans, don't underestimate their power, and how much more can be had, JUST AS CHEAPLY AS A SBC, except it's more reliable. Number four, and this is my opinion, FWIW, Un-channel the car, you'll be amazed at how much more legroom and comfort you'd have in it, and that really is how most track t's are anyway, unchanneled with a belly pan. I say go for it! I've had two T's , and yes, I'll admit, mine both had 440 Mopars in them, but I've always had mostly big blocks until recent years.
I hear you on 318s... I grew up with Mopar muscle cars as daily drivers, so am used to BB power and torque.