Best Of

@LDR as far as the Fill and vent pipes they can both be 1 1/4, or 1 1/2 or 2" but they have to be the same size.

In some locations in the old days the fill was 2" and the vent 1 1/4" but they changed that many years ago.

Any second hand tank will have problems since there have been tank bottom deposits building up from the first delivery all the way to the last delivery.  How old is the tank?  What is the condition of the outer steel tank?  Is there stuff other than oil in the bottom of the tank?

The thing about steel tanks is that they rot and rust away from the inside as well as from the outside, so you really can't tell the condition without expensive testing which makes a new tank less expensive than testing an old tank.  With the plastic inner liner of the Roth tank I would feel more comfortable with using that for a good long time if it is in good condition. 

I would just take the time to thoroughly clean the junk out of the bottom of that tank.  That would involve about 40 gallons of clean oil and a pump with a garden hose spray nozzle on the end of the pump’s discharge hose.  Then I would take 10 gallons of oil and wash the bottom like I was spraying off the driveway with your garden hose.  After that was done I then empty that oil and take 10 gallons of clean oil and repeat.  Then another 10 gallons and repeat.  By the time you get to 40 gallons you should have a clean tank.  You need to suck out as much of the dirty oil from the tank as you can each time before adding clean oil for the nest wash. 

The Roth Tank has special fittings on the top and they convert to standard 2” pipe thread for easy connecting to the fill and vent pipe, vent alarm and the top feed fittings.  

Other than that, you just make sure it is on a flat level surface in your basement and install it like you would install an oil tank according to the code.  It is a tank full of combustible liquid in your basement, you know.   Do it right or don't do it at all.