Actually any gas price is better, the more gas price, the more faster transaction, the more faster you will receive minted PoSTokens and The more fees you will pay 

It was no joke but still jokes aside, 1 gwei is nice line between faster and cheaper transaction. So go with it, choose gas limit 200,000 (200k) and send 0 PoS to your own address (where you are holding PoSToken).

Once transaction get confirmed you will get your reward but remember ethscan and ethplorer are bit late in updating balance, so go here: https://calculator.postoken.org

And enter your addy if it shows 0 then you can have peace of mind that it was successful.