If I have strep throat, can I transmit it to a mans penis through oral sex?

Yes. Strep is a contagious bacterial infection that can be spread via bodily fluids through any susceptible skin barrier, usually the mucous membranes, such as the genitals, nose and mouth. So take your time, take the medication and make sure both of you are well before engaging in oral sex.
CONSIDERATE. Very considerate of you to be concerned. There are many factors to weigh, but since you can transfer strep to mucosal tissue, why couldn't you transfer it to the lining of a urethra? Are you sure you want to do that?
No. The strep that cause strep throat are unlikely to affect him there. I hope you've been treated for it; you probably become less infectious for other sites in a few hours.