When should I consider an LT1 swap?

Howdy group...
I have a '95 Z28/SS clone with almost 150,000 miles on it. I've always taken care of it and changed all fluids routinely with synthetic, and even
flush out the crank-case every-other oil change. There's no leaks, and I only see the occassional puff of smoke from the exhaust when I really punch the pedal during a fast launch at high RPM. ...Honestly, the motor seems about as strong as it's ever been.
The rest of the car is also well maintained and aside from the typical fixes here and there you'd be hard-pressed to guess this car had any more than 60-70k on it.
As for mods, they are only the basic ones: Borla cat-back, 1LE elbow, throttle-body air-foil, SLP/SS suspension, etc.
I've recently retired my ride as a daily driver (hence the high mileage) and have decided to put some cash into renovating and speeding it up for those summer cruises.
In a perfect world filled with cash, what I'd really like to do is drop in an LT4 and supercharge it, but I'm not sure it's worth blowing the bucks on such a radical change if my present LT1 is still running strong. That being said, is my motor too geriatric to consider any serious modifications? For example, is it worth putting the time and money into putting headers in, only to swap the motor out in a year or two due to failure? ...For that matter, would it be suicide to (gasp) supercharge this LT1 with 150k on it? Is there a typical mileage cut-off for when you should not consider doing any major upgrades to an LT1? I've been told that a motor with high-mileage can't really handle mods like this, but I've also been told that the LT1 is an extremely durable motor good for 200,000+ before major renovations become necessary...
I'm stuck here, because it seems silly to take out this motor and go through the aggravation and expense if there's still enough life in it to still tweak it without making it explode. What should I do?
As an aside: if I were to consider an engine swap at some point, would you recommend another younger LT1, an LT4 (corvette), an LT1 converted to LT4 with the available kit (I hear this pumps out way more power than a stock corvette LT4), or an LS1? ...I've been told that the LS1 won't fit into LT1 F-bodies without major mods (including a taller hood). I'm not a bank, and likemost hot-rodders, I'm looking for the most bang for my buck...
Any opinions/insight? Thanks, and sorry for the long-winded post!
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