I will answer this based on boost from a blower, as thats what I am familiar with and have ran for 25 years, I would not take the chance of 6-8 lbs on a "stock" motor simply becasue your stock motor is 25 years old, if it was a fresh rebuild with stock components I would run 3-5 lbs maybe, and yes you will get a thrill with 3-5 lbs, heck even when a supercharger or turbo is not on boost it will greatly improve power as its still providing much more volumetric effeciency over normal aspirated, even at 0 lbs of boost you are at 100% VE something tough to do with a high performance motor without a bunch of work. As for streetable, the more power you get out of it the more "picky" the motor will be on fuel quality, quantity & air temp, its just the way higher horsepower motors are, watch the drag races in a cool evening and you will see what I mean. I wouldn't even think about this unless your "stock" motor is rebuilt or in 100% shape, not a daily mode of transportation and even then run low boost, before you find out what the "weak link" is on the motor. I run 5-6 lbs with forged pistons, 4 bolt main and rebuilt rods with ARP bolts and a much larger fuel pump and lines than stock (1/2") and have good luck
As for the turbo kit, you get what you pay for and those chinese bearings will be humming on a turbo I am sure, buyer beware. As for the transmission I will let someone else more knowledable answer that.