sure, that's the easiest way as long as you note down or know the chords.
Saving your easy recording as midi will not save the accompaniment anyway, but you aren't interested in that, just the melody line for lead sheet. I would quantise hard and don't use the pitchbend or modulation wheels or volume pedal.

Load the midi into your computer sequencer program and select channel 1, which R1 should have been on. Most programs have a chord input function which consists of just typing C, Am, Dm7 etc and, for example using the space bar to jump to the next measure point requiring a chord change. You can even play the original recording in the 7k at the same time at a very slow tempo and write the chords in the program as they come up in the screen, complete with the correct measure numbers.

When finished save, then look at the print preview page and see how it pans out. You can usually play around with the sizes of how many measures you want across the stave, and whether you fit it all on one A4 page or go for big fonts etc and spread it across two or more pages.