a stock 4bt aint shit.
power and weight of one are not serious issues that would injure a good condition ranger frame with hydro mounts.. looking at 750-1000 pounds depending on your trans selection for a 4bt...an e40d or 4l80 or allison being the heavy side... many run 820 pound engine trans combos...
a older 4 cyl ranger with auto is about 620 ish iirc.
conversely...yes a mere 100 pounds is allot of extra weight over typical front suspensions and can effect pure balance for most vehicles..so most think that 2-500 is murder. with tib/ttb rangers things are different...torsion sla are pretty stout and easily tuned as well.....beefing up the spring rate on a sla/coil chassis is a little trickier but not overly hard or complicated.
the sla joint issues are weak points, the tib ttb not so much.
with v8 swaps initially i thought the weight was an issue until i realized it was the torque curve/hp combination that affected the handling more then weight. this was readily apparent with alum hi power swaps and turbo 4 trucks.
theres guys here with 2-250 pound front bumper winch combos that think a v8 weight increase at the axle would be bad for handling
....but didnt notice much with the monstrosity hanging off the front with two huge batteries.
so its all relative to actual build goals. prerunner obviously needs a tight balance...general use just needs to be reasonable.
i daily drive my truck with full width axles and a 6.2 diesel/4l80 setup that weighs about the same as a 4bt setup and it drives pretty good for the low power it has.