Need help with this vacuum reading

for gear try a minimum of 3.73.

If you had a manual trans you could get away with less but you don't.

BTW not having enough gear for a given converter will cause the trans to have 'heat' issues, at least with most cause chances are you'll be slipping all over town till you get on the freeway. You wanna try and get your cruise rpm into the converters lock up band, if that makes to you, by lowering or numerically raising the gear ratio.