best recorded 78rpm to look for, also cartridge...

Find a cartridge that takes a 3mil stylus. Pickering & Shure both had some. Other may have as well. The tip size is giving you the problem, not that it is a Pickering D750.

The speeds of these old records actually varied somewhat. At some point they were standardized at 78, so having variable speed capability on your turntable for the earlier records is desirable.

There also wasn't a standard equalization curve at that time, or for early LP's, for that matter. There are phono preamps available (from Graham Slee, for example) to compensate for this.

The Pickering D750 is a stylus, not a cartridge, that is designed for stereo playback. You will have much better sound reproduction if you use a mono cartridge specifically designed for playback of 78 records. In fact, using a stereo cartridge (stylus) on your 78s will surely damage the record grooves.

I have used a number of them, mostly from Ortofon and Grado, but there are others. The stylus tip size you will need depends on your 78 records and when they were made - sizes range from approx. 2 mils to 6.5 mils for old acoustic playback platters. You will probably be safe with a stylus tip size of 2.5-3.5 mils.

While 78s are anything but high fidelity, they can sound very good if used in the right system and you can get the turnover and rolloff correction (equalization curve) right. But IMO the main reason for playing 78s is not for the quality of the music, but because you will find a whole world of music that has never been recorded in any other format. Have fun.

I have a single ended Tube player which I purchased from an Audio Visual Dept. sale at the local Elementary School.I cannot record from it but when I put A Blind Boy Fuller 78 on it ,I'm in heaven.The brand is Newcomb.

Audio Technica, Grado, Ortofon, Pickering, and Stanton all make (or made) 78 rpm carts that are safe recommendations.

I'd stay away from the current Shure 78 cart. Its sound quality isn't in the same league as the others, IMHO.