I've been toying around with the idea of going for a rack and pinion conversion or just rebuilding my power steering (total rebuild) wanted to know what most folks are doing, or would do if they had time/money

 

Go with R&P, though with that 67, be prepared to have "armstrong steering" if you go with manual R&P. Not sure which, if any, of the R&P kits now have a power option. I chose the manual R&P for my 67 and I love the quick responsiveness of it, though it is a bear in the parking lots and tight corners...

 

There have been some really great threads on this subject. Either way you go there are some real pitfalls. I'd suggest spending as much time searching and reading the threads as you can.
There is another option, but I don't know anyone who has done it yet. You can get an actual power assisted steer box that will work in place of the stock box.
Here's a few things you don't hear:
I'm running one of the two most highly regarded power rack and pinions. It's good, but it's not great. It's a rather quick ratio at less than 3 turns lock to lock, and takes a bit more tip-in effort than to continue turning the wheel. They also take a lot of caster to get a decent return to center (which increases tip-in force required), which pulls your front wheels forward in the wheel well.
You'll read about the loss in turning radius (mine and the TCP should be about 43' same as an extended cab Ranger on a first gen Mustang). Header fitment issue can be a problem. Yada, Yada, et nauseum.
Again, there are a lot of really informative threads on this whole subject including manual or power, rack or recirculating ball, etc. Some thorough reading will put you in a good direction.
I've just tried to bring up some of what you don't hear.

Good luck,
If you'd like to see what a rack install looks like in a first gen Mustang there are some pictures on the web site in my signature.

 

I've rebuilt my stock system. It's about 3 turns lock to lock, but I plan to add a steering quickener (1:1.5 ratio) when I get the time (and find a good place on the shaft to mount it).

 

I actually prefer my setup over the suggested items.

Power steering gear box with manual steering. Throw in a a roller idler arm to reduce steering friction and I have a setup that's a quick as rack and pinon without the expense and reduced turning radius. Just my $.02
Your experience and budget may vary.