as for the dist. not fitting a 348 , there is a aftermarket spacer available from ,lamar walden (hes is the guru of a 409 ) for a 348/409 to standard gm dist .
the 348/409 shares many of the same parts as smallblock/or bigblock chev .
oil pump smallblock
drive for oil pump bigblock
lifters bigblock
rockers big block
valves ford /chev
springs smallblock
crankshaft , with some machining makes a stroker motor
and now msd makes a dist for a 409/348
hope this helps