150k equity does sound like a good cushion but if the property is worth $600K, that means you are at a 75% LTV already, which for a revolving line of credit is pretty tight.

I could  do a FHA loan with the $4k but I want to have a bit of a cushion to work with when things go wrong such as various capital expenditures.

Once those are factored in, you're looking at a couple hundred bucks in positive cash flow, which is not enough cushion in my opinion.So, you're not going to be making a bunch on money on this property as a straight rental.Given this, your best bet is to sell fairly quickly and for top dollar.

With the items you listed, you may need to budget for: 5% vacancy, 8-10% repairs and maintenance, 8-10% capital expenditures, and 10% property management.Breaking even on a property may be better than selling it for a small loss but if it were me I would want some cushion in my analysis.

I'd use the equity in your home as a DP for another deal or leave it as a cushion till you get your feet under you.

This way you have a lot of equity as cushion just in case the market heads the other way.

More money you make more cushion for real estate.

I would either look at raising the rents a little to provide a little more cushion or possibly selling and reinvesting that money if you have any equity.  

If the end-buyer is using a mortgage you are likely looking for extended term transactional funding, which is very similar to a short term hard money deal but typically with less equity cushion for your funder.

Having some equity cushion gives you some protection.IMHO, you need three factors for a rental property to be a good deal:1) cash flow, per the evaluation we all discuss and debate2) equity, at least enough to cover your costs and to protect against some downward movement.3) demand, if you can't fill the units, its not a deal at any price.Two out of three is not good enough.