I have the opportunity to buy a small 3/2 SFR in a B+ neighborhood actually just down the street from my own house the Indianapolis area.

Also, you may have to overpay to be in a really good location so sometimes a B+ or B- that is gentrifying into an A+ (don't predict the market...but this is were we have done really well) is a great strategy as well.  

Last summer we had 75' under asphalt 4' excavated and replaced about 30' of old 6" concrete sewer line with 6" green ABS for $5028 all-in, including 8% sales tax.

If you expect it to appreciate and your cashflow really is $5k/yr after all expenses, your ROI time is about 4ish years which probably makes it a B+ investment. 

Purchase a B Class asset below market.

Where are the best places to invest in A, B and C+ SFRs properties? 

Your R+M will likely be higher than an A/B, but I don't think it's unreasonable to get under that.

On maintenance and CapEx I usually account for 5% each of the rent but, just know that the rule of thumb is 10% for each --- It depends on your property class - A, B, C or D/warzone.

Look out of state (midwest) and get a solid A/B class asset (think 75-150k, 15-25% down) that'll rent likely for 8-1700 mo.

They close it a-b then resale b-c.