Rectos just don't sustain very well compared to lead amps of the past. Cranking up the power amp and playing loud helps noticeably, but even then, if you want the kind of lead note sustain that classic rock is known for, you're going to need some help. OD's, EQ's, treble boosters, clean boosts and compressors up front all can help and can even completely fix the problem depending on how you set them. Reverb won't add the slightest bit to your sustain because the processing occurs after the generation of the complete signal. Delays can help somewhat since they feed signal back into the loop, but they rarely do the complete job with a Recto.
A combination is usually the best solution. Stick a clean boost and/or a good harmonically-rich OD up front. A treble booster can also be substituted for either one. Pop a graphic EQ into the effects loop with a slight (2 to 6 db) boost at 800Hz followed by a delay with a medium-to-long delay setting. If you want reverb, place it at the end of the effects loop chain (never up front) after all the rest. Set your amp's mids to noon or better, your bass to noon or less, the treble at noon to 2:00, and the presence wherever you prefer. Do all of this and play at slightly louder than bedroom volume and you'll have all the sustain you could ever make use of.
