Same reason that chick wants to drop a 40k V8 or whatever into a R31
First of all, making comments about I & H like that, clearly you do not know what you are talking about.
The debate will run forever about which is best.
Its application dependant, simple as that
Again no ideas. What are you worried about cranks for?
20k budget wont even get your head to 10,000rpm. Let alone 12,000
So I wouldn't be getting too excited on which stroker etc.
Realistically to even sit @ 9,000rpm reliably your budget has already been blown out of the water before you start as there is probably 5k in the head alone.
20k on the street/running is as simple as a 25/30 with a mild freshen up of the bottom end etc.
Otherwise you go chasing super big power and RPM everything from the gearbox to diff & driveshafts needs attention. Then there is getting it to the ground etc etc. Just in driveline you'd be looking at the 8-10k mark.