Need power, Chevy small block or big block??

I was gonna say my dad had a 76/77 blazer I think it was with a 350 and a th350 and 35's with a body lift and he put a bigblock in it a cheap 454 but that thing had some towing balls needless to say he broke all the ujoints and sheared the both drive shafts not from beating it but just towing one time we were just pulling the jetboat out on a steep angle we let a friend doit and he just kinda gave it to much gas and the rear drive shaft was on the ground. Nothing special no headers no big cam no big manifold just a fresh running 454 just something to keep in mind  

stempak:
I was gonna say my dad had a 76/77 blazer I think it was with a 350 and a th350 and 35's with a body lift and he put a bigblock in it a cheap 454 but that thing had some towing balls needless to say he broke all the ujoints and sheared the both drive shafts not from beating it but just towing one time we were just pulling the jetboat out on a steep angle we let a friend doit and he just kinda gave it to much gas and the rear drive shaft was on the ground. Nothing special no headers no big cam no big manifold just a fresh running 454 just something to keep in mind

This is no surprise. It likely has tall stock gears and when towing you are putting drive line average torque above design limits and it fails. Many never consider this but you need to regear with bigger tires. Using bigger motors instead to try to "cure" this just creates other problems.  

The 350 was the original tired motor.Ya I think the gears were 3.73's one of the drive shafts just twisted. everything was in perfect shape, the turbo350 I don't think everhad anyproblems it just had a trannycooler and that was it  

383 with some AFR's atlest or brodix heads and like 11.1 comp. If you want to run it with like 95 or 100 octane once in a while you can run with more advanced timming and gain alot more power. at 11.1 you will need 92 minimum. you will have a raw sounding motor it will sound like a bigblock but still a mouse motor  

Will Vortec heads bolt to early 350 block 1970 vintage?  Will the vortec head give you low end torque?  

yeah the vortecs will bolt on to the vintage block but you will need a vortec intake not the gen 1 intakes....from what ive heard vortecs are more mid range and top end performers..but if you have a healthy motor with good gearing for tire size you will be fine..  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

Try putting the TBI injection system on the Vortec motor. My brother did this to his 89 Jimmy and it had alot of low-end torque. I don't recall what intake is used to do this, I never did much research on it and never really thought I would do much with the knowledge. I'm a BBC guy.