I have used spiders before where they are either the 3 pronged one and a tight fit or the spiral type which spring into place.
With the 3 pronged one fit said adaptor onto turn table and then centre the record with one of the prongs directly where there is a gap. Where there is a gap, fit a small piece of packing plastic to bridge the gap between prong and record. When you have desired thickness to fill the gap, glue said piece to the prong near the gap. With a plain label you can put a dot or two so you can easily relocate said adapted spider or mark the spider and line that up with something on the label.
With sprung spiral spider they are usually bigger than a standard hole , so centre record up on the deck, place sprung spider over spindle and trim each leg so it fits snugly into hole or not if one of the prongs is a fit where said gap is.
Hope that makes sense????
Dave H