To be honest given the biasing on the input amplifiers, the "transparency" of any of the capacitors in the circuit is irrelevant as the circuit leaves any pretense of linearity or accuracy at the input jacks. Grid leak biased circuits do sound beautiful though and the asymmetrical impedance that presents to a guitar pickup is one of those things of beauty nobody seems to ever have got right in silicon.
I'd go with whatever you can find that meets the voltage ratings of the various sections. Any plastic in the signal path is going to sound better than a ceramic, but arguing over which sounds best in a magnetic echo is kinda like tube rolling. The best sound will disappear behind a mask of non-linear magnetic noise.
Out of interest is this a tape or a drum? It kinda looks a bit like a Binson, but there were a gazillion clones.