For Macca's sound, it depends
which sound you want: Early (early) Beatles would be short scale, roundwound hollowbody. Anything later, it's catch as catch can: Macca used (mostly) the Rick 4001, the Hofner, (believe it or not) Jazz basses, other Beatles playing Fencer VI's and all sorts of odd stuff. From what I've heard, he preferred a blend of DI with a Bassman amp (mic'd) for recording. Not sure what he records with now, but my ears can't deny the sound of his current stage rig - Mesa 4000/215 or 1516 (1x15, 1x10, 2x6, and a tweeter).
Phil's Sound - Depends a little on the vintage you want: First: Phil almost always plays with a pick - very few exceptions, but if you've listened to as much of Lesh as I have (a real lot), he's a pick player. So, if you are a finger style guy like me, you need to manage the highs and mids in your tone very carefully.
Early Dead - Phil played an unmodified Guild Starfire (which had the pickups that became today's Dark Star pickups)
Later (1969ish) - Alembic modified the EBO to take a pair of the Hagstrom/Guild pickups and added an "emitter-follower" circuit - arguably the first active bass preamp.
That bass was stolen and Alembic did a massive renovation to the Starfire, with a new neck and newly-minted Alembic pickups and multidimensional preamp. This is the Europe '72 sound.
Throughout this entire time, Phil was using Pyramid Flatwound strings. They cost a bundle ($70ish a set), but they actually contribute to that straight harmonics with a strong woody touch sound Phil had. Along with the short scale of his basses and all the pickup and preamp, plus Phil's quirky, syncopated technique, and you've got most of it. Also, during this period, Phil played mostly through Fender Dual Showman heads or just the preamp from the Fender (which became the Alembic F2-B preamp) and a power amp.
By '73 or so, Phil was playing a medium scale, solid body Alembic with very exotic electronics. Subsequently, he moved through Doug Irwin basses, Steinbergers and ultimately to a custom 34" scale (the ones you see on the market are 35") Modulus 6 string.
If you are trying for Phil's earlier sound, probably a pair of Dark Stars on a short scale, mahogany bass with Pyramid flats, played through a pretty clean tube amp will get you close enough for government work. Almost any Modulus can nail his current sound.
