Blasters were never designed for top speed. The small blaster was a cheaper quad designed for a little more playing. They are great for trails/woods riding and can beat most larger quads with a few mods and adjustments ($$$). although to compete with say a new 450, unlikely.
I also dont suggest changing your gear ratio. here's why:
1) blasters not designed for top speed / high RPM for extended periods like 72 mph for miles
2) top speed increase = bottom end losses (more clutching)
3) 240 is a bit for a completely stock blaster to get up and go (relates to #2)
If you did more mods, a gearing change would be more probable.
1) head mod
2) porting
3) you already have a pipe so good job there
4) carb size depending on pipe (i think you have pro circuit? i dont have experience with such pipe)
If you still want to go faster after this, heres the tips
1) larger gear in front (14 fits, 15=stator cover trimming),
---smaller in rear (38 requires different hub) = more top end speed (loss of low end power (get-up-n-go), more clutching)
2) larger tires always help too (looks like you have 20" so probably not go bigger with stock swinger)
3) always change sprockets and chains at the same time! all new or no new!
---- here's why:
lets simplify this with my awesome MS Paint skillz
the rollers of a chain are a specific distance apart center to center, designed to exactly mate with the correct sprockets..........
View attachment 24428
a new sprocket for that chain has it's teeth peaks and valleys that exact distance apart for the chain rollers to engage smoothly and fully
View attachment 24431
you can clearly see the very worn sprocket on the left has wider valleys and greater distance between the teeth peaks and will not engage with a new chains rollers or spaces cleanly, which will quickly stretch and wear the new chain to fit the incorrect peaks and valleys of the worn sprocket.
as will a stretched/worn chain wear a new sprocket to match it.
worn and mismatched chain/sprockets is the #1 cause of snapped chains and busted engine cases when the broken chain whacks them
At the end of all this, the choice is opinion based and effectively 100% your choice
