Switching from primo to mast midcycle

Been running 500 test, 175 primo for 8 weeks. Long story short, I think I can push it to 16 weeks, but I'm almost out of primo, but have plenty of masteron on hand. I assumed the primo was 200mg/ml when i ordered it, but it's only 100mg/ml, which is why I ran out.
Never run primo or mast before this, so curious If switching to masteron is a reasonable option, or if finishing out on just 500 test makes more sense, AND WHY?!