I'd probably use a 23/26 guage thread and a #16/18 needle, if that's what I had. Otherwise I'd use what I had.
If you want black thread V69 UV stable polyester, order from Sailrite.com , they specialize in exactly what your doing, the hobby repairs, its about $12 a spool.
get a needle threader, they cost about $1.50, it stops yelling at the thread