.......If you have files and are willing to retooth, I advise getting some wide masking tape, sticking it under the toothline and marking lines every half inch 90 degrees to the line to keep your spacing.
You don't need a fancy printed tooth profile......
Tom, you are a far better saw sharpener than I if you can eyeball a consistent tooth spacing from marks 1/2" apart! I always use either a paper template, with a mark for each gullet (they are available on the web,
here for e.g.), or use an existing saw as a template.
You
can cut new, smaller teeth over existing ones, but only if the new pitch is a multiple of the original. Another alternative is to take the saw to a saw sharpening place & have them cut new teeth at the pitch you desire.
Saw-sharpening has a steep learning curve & there is a world of difference between a well-sharpened saw & a poorly-sharpened saw, so it pays handsomely if you get it right.
Cutting in new teeth from scratch is hard on a file, & given the rubbishy things that pass for files nowadays, be prepared to use up a couple of files converting your saw. You will also need some help in keeping rake angles consistent, at first. This is the simplest way I know:
Rip teeth are very sensitive to rake angle - 5 degrees (negative) is a moderately aggressive rake for hardwoods, and I usually ease it back to around 7 or so for people who aren't very experienced in using saws. You'll find that cuts a little less aggressively (but still quickly enough if kept sharp) and starts a bit easier. You can feel a difference of just a coupe of degrees of rake angle with a ripsaw, unlike crosscuts, which are nowhere near as sensitive to rake (they typically have rake angles more like 12-15 degrees). Crosscut teeth are more sensitive to fleam angles, which are typically around 20 degrees, but can go much higher.
Anyway, a rip pattern saw is the one to start with, imo. With small saws (12 tpi & up) you can file all the teeth from the one side. While not generally advocated by the pros, it's easier to keep the teeth consistent when you begin by working from one side only, just keep the file square to the saw. Once you feel confident and can get a consistent result with them, you can move on to crosscuts. With two angles to keep constant (rake & fleam), you'll have your hands full to begin with, With a crosscut, you are virtually constrained to working from each side, and the change in stance & angle at which you are filing makes it hard to keep each set of teeth consistent.
It's definitely worth becoming competent at sharpening saws, a sharp, well-set saw is a pleasure to use, as well as being faster & more accurate. I reckon there are far more dull saws in the world at any given moment than sharp ones....
Cheers,
Ian