tell me your 440 combo
First of all, 360s are pretty plentiful and one way or another, you are going to be spending money on building either motor and I would still recommend a 360.
On the flip side, the late model 440 is going to be running low 8's compression-wise. Instead of porting the late model heads, I would consider putting money into slightly higher compression pistons and other internal components and think about beter heads.
There are really several options for you here. Consider that the stock 440 in my GTX was rated at 375HP stock (that is with a 10.25 compression ratio though). Upgrading the induction system and adding headers is going to get you were you want to be.
Again, I think the 360 would be nice in your '69. Having a very similar compression ratio, some headers, 2.02 heads and the right cam will get you to 400HP too.
You may also want to consider what other components you may need to upgrade as well (ie. trans, convertor, rearend, etc.)