I am replacing the very old electronics on my 1977 Hunter 30 sailboat.

I want to use the Raymarine ST40 bidata instrument, but I wonder if I
can use the existing transducers for deptch and speed. The old depth
is a Standard DS1.

Any thoughts on this? If not reasonable, do I just install the new
through hull transducers and leave the old ones in? or remove the old
ones and try to fit the new ones in the same holes?

thanks,
Buddy E