I don't believe you can just rent to section 8 without having gone through the approval processA rental becomes Section 8 approved when the landlord accepts an applicant with a HousingChoice voucher and requests their local Housing Authority conduct an inspection.

If you lack the constitution to be the boss of your property - to conduct inspections, enforce the terms of your lease agreement, communicate with tenants from a position of authority then you should consider a property manager and see if they do better with your asset.

The longer answer might be to talk to the permitting authority and find out from them how much would be grandfathered in - if any - and how much really has to be re-piped.

This is really a question for the housing authority, not here.

Setting aside qualifications, the conclusion that I reach is that parties would tend to prefer the remedy of damages for breach of contracts to produce things, whereas they would often favor the remedy of specific performance for breach of contracts to convey property.In footnote 3 the author noted:3.

Be prepare to deal with tax authorities at some point throughout the process. 

We have some sharp people here, some with just a couple years of experience in real estate, but they are a formally educated crew that can really be full of themselves and speak with the same authority as if they had been in the industry for 40 years.

Unless both the circuit breaker for the heater and the local disconnect are locked inside an "Authorized Personnel Only" area, the tenant(s) can always shut the heat off.

My question is: will the section 8 authority turn down a lease altogether if they think the rent is to high? 

Read books from Bigger Pockets authors, podcasts, independent research, talking to other investors, and pounding the pavement.