What also gets me here is that the only difference in what I want to do and what it is now is the internals. The block will not be changed at all. To say that saving the virgin block is a good thing is kinda ludicrous because it has already been machined .030" over and it is not going to ruin the block or anything.

 

Well, I forgot one thing. The roller block is machined for a one-piece rear main seal , while the 289 is set up for a two-piece unit. You can machine the 289 block to accept a one piece rear main seal, but you'd have to do that in order to swap cranks between the two blocks.

 

Using GT40 heads you might as well build a 302. You won't get any more power out of a stroker, it'll just make the power at a lower rpm.

 

GT40 heads are just a set of heads I have for now. I plan on buying a better set of aluminum heads down the road of course.

 

You need good heads to feed a 347.

 

While I completely agree, I ran some '68 J code heads with big valves, upgraded valvetrain, and port matched exhaust on my 331 until now. Worked fine until I finally picked up a set of Trick Flows.

 

It'll run fine, there's just no sense in spending money on a stroker kit when you have a crank and rods that will work. If you plan on upgrading heads later, then yeah. A 347 though to really make some power needs some good heads.

 

even with crappy heads a 347 will make at least 50 ft lbs of torque more than a 289, probably 30-40 more hp if you didn't change a thing.

 

It'll make more torque at a lower rpm, so the horsepower peak is lower also, but the horsepower is generally about the same. The smaller engine needs more rpm to make the horsepower(less torque) so it needs more gear also. The 347 will run better at lower rpm though.