question on math course for next year; considering pre ap algebra 2 should be fairly uniform a course offering across most locations, I'm hoping folks might have some opinions on whether this would make sense for my ds15/turning 16 this summer.

He was homeschooled in middle school, took algebra a couple of times, due to unidentified learning disabilities - adhd and asperger's, which slow him down (more like algebra spread out over 2 years, and other stuff, like Trig, thrown in here and there).
He did well on this, completing a good video based course at one
point.
He took a placement test before going to h.s. last fall, and was able to get into geometry, but not advanced geometry.

He got an A in the geom. course, and finished very well in his end of year exam.

He wants to take pre ap alg 2, because he (and we) think the regular alg 2 will be a bit slow for him, and therefore fail to keep his interest. He is also taking pre ap chemistry, those will be his challenge classes, if he can get the math he wants.

THe issue is, he did not take 'advanced geometry' - so they are indicating this pre-requisite of adv. geom. may keep him from getting into the pre ap alg 2 course altogether (and, we are not sure, but possibly other more advanced classes -- but that is another conversation).

He has always had high math comp. scores, and lowish to abysmal math computation/speed scores -- although with doing math most days this school year, his accuracy has picked up -- his speed, not so much. He stated in his IEP meeting that he still needs accommodations for time on tests, some of the time.

he also took a pre ap BIO course in which he is doing very well - A, the teacher speaks of him in glowing terms.

So, if anyone has an opinion on this please let me know:
do you think slower speed is going to result in a VERY hard time for him? (if they let him in)
what content is in the advanced geometry course, potentially, which might be missing from what he has taken already? (we have summer to have him pick up any missed material, in other words)

thanks in advance!