17 and in need for power!!
^Very good advice
If you're dead set, though, on playing with it, I would suggest neither? If you are going to go to a v8 swap eventually, no sense pouring money and time in to making it boosted if you're just going to pull it (don't get me wrong, boost is great if you are wanting to make more than, say 250 horse with a slant, but WAY more complicated than N/A)
The better condition your slant is (even compression, no blowby or oil burning) the easier/cheaper this will be
Some good builds to look at are found here...
http://www.slantsix.org/forum/viewtopic.php?t=23314
note: as usual, to keep it cheaper will be to build it less. A cam with duration around
[email protected] is about the most you want to go with a stock converter
Please, though, whatever you do, don't slap a set of headers and a 4 barrel on it and then complain that its awful. Its not hard to wake a slant up, you just have to match your parts and do it right. Don't buy directly from Clifford (only thing decent is their short intake) don't buy Comp Cams (get your cam and lifters reground, Oregon Cam Grinders is good people, plus endless cam specs
https://app.box.com/s/a00t8svaib0jqevitapq) and distributor recurves along with carb tuning will are neccesary
You'll have fun!