Fuel injector pump replacement 300 TDI engine – please help.

Hello to everyone.
I am new to the subject with the fuel injector pumps.
For better reference see all pictures I applied.

I have a 1997 300TDI with EGR Land Rover Defender 110 Hardtop.
My engine is a 21L (see images below), EGR is blanked, not removed.
I have no immobilisation. There is an iron rope/ linkage between the throttle and the pump itself.
The numbers on my fuel injector pump,s shield with an EGR device are:
Bosch 0 460 414 099 ERR4046.

My questions are:
1) It is possible to replace it/interchange it with a Bosch 0 460 414 093 ERR1985 (see images below).? Will my car run smoothly? By doing so is there any possibility for ruining my engine?
This pump comes from a freshly removed still running engine and I know for sure that it is functioning properly (see pictures for more reference).
2) I notice that between the pump body and the engine block itself on my original pump there is a linkage with a spring (see picture) and on the one that I potentially will fit there is no such spring.
What is the role and function of this spring. Could it be that the previous owner could have removed it, or the pump was manifactured by Bosch without this spring for a reason?

Every personal experience, advice and explanation would be much appreciated.

Thank you in advance for your answers.

Yes it will work, I think the spring widget is some sort of cold start device, advances timing when cold or something like that.

The 300 uses several versions of the ve pump, main difference is the inj pump timing as some have different amounts of lift, in practice any will work.
Basically the newer the 300 the more emissions were getting tighter so they started to fine tune the fuel system.

please take a picture of your number 4 injector - the one closest to the driver