Best response to your question is "it depends".
1. Number of international planes landing before during and after your plane arrives.
2. Check baggage or carry on only?
3. Delay time of departure in SXM.
Not sure about minimum layover time for international air travel but I thought it was an hour which would mean 70 minutes meets the requirement.
4. In your favor is that Wednesday normally means lighter traffic and faster C&I than Sat/Sun.