Superglide,
From a "buy and own for twenty years" point of view, yes, what you're saying is the path on which I am traveling with my 97 Boxster. When the motor blows I will probably get a Raby rebuild. I've already replaced most everything else.
However, I am always keeping something in the back of my mind... I am sinking thousands of dollars into a car I will never get back. Period. I have $38k in my car total in five years. It's still worth just $12k or possibly $13k. A Raby rebuild may take it up to $18-$20k max, but I'd have $52k in it by then.
This is what keeps most guys from doing what you're talking about. It's not like taking a beat up 69 Camaro and fixing it up. Every part costs more on our cars... sometimes ten or twenty times more, yet the return on investment is not there.
I tell you what though... if my motor blows anytime soon as broke as I am right now, I will try to shoehorn a Corvette motor in it. Much cheaper and well, it would be a good conversation starter at DE events, that's for sure. Half the 911 crowd would be pissed off because I diluted the brand and the other half would be amazed after I whipped their butts in the straights.
I don't know of anyone to do the vette motor as of yet, but they do it in 944's and guys are talking about it so someone will eventually try it. Heck, if you can find a beat up boxster for $10k or less, why not?