How many base gaskets can I safely stack up to shim my airsal 52mm cylinder up so the intake ports are completely open when the piston is down???

 

IMO: prolly 2.
Is this a ported cylinder?

 

Wheres the bottom of the exhaust port?? You'r cylinder is setup for a different stroke crank like a 45 not a 42 in your bike. That doesnt mean it cant be fixed. How high is the top of the cylinder from the outer edge of the piston crown. It should be almost even. You can space it up with even 3 gaskets but make sure you get them stuck to each other really well or it will usually leak at the bottom of the cylinder under the exhaust. A spacer plate is a better idea or throw a different crank in to fix it.
What you really need to do is use a degree wheel and degree your ports and space the cylinder where it needs to be and then measure the squish clearance and get that fixed or it wont run but 70% as good as it should. If you dont have a degree wheel and wanna pm me your email addy. i can email you a printable degree wheel and give you some specs you'll need
The airsal cylinder is not my first choice for a short track or trail cylinder. For dunes or dragracing it's ok. Hope this helps...