You can use the calculator on this page to see gain needed for a particular output. For example, for 0.8 mV output you need gain of 52 dB.
Details of how they arrive at this value is explained in the page.
However, gain matching is only one aspect. One also needs to match the compliance of the cartridge to the effective mass of arm. 14/15 cu would put the cartridges in mid compliance range. SME IV effective mass as per SME's web page is "10/11" gram which is mid mass, so ought to be a good match for the chosen cartridge.
Details of how they arrive at this value is explained in the page.
However, gain matching is only one aspect. One also needs to match the compliance of the cartridge to the effective mass of arm. 14/15 cu would put the cartridges in mid compliance range. SME IV effective mass as per SME's web page is "10/11" gram which is mid mass, so ought to be a good match for the chosen cartridge.