My opinion really don't matter,, what the judges opinion is ... who knows.
In the olden days ProStreet meant anything with big pfhat tires all around. I built my 66 originally with 15x15 Convo Pros and 33x22.50-15s on the rear, and 8.5x15's with a 9.25" wide radial on the front (MAN that pig was a bear to drive with the manual steering box!!) ooops,, back on topic.. Went to a show and got stuffed in "Street Rod" class
The folks putting on the show will dictate the class you fit in, in 'their' show. Be sure and talk with the officials so some judge doesn't blow you off because he don't think your in the 'right' class
Good luck,, whatever you choose I bet you do well. Nice truck!!!