Amp gauge shunt

I have be reading a number of threads related to alternator upgrades. The Mad Electronics method of eliminating the amp guage looks good eliminates the guage, but I really don't want to drill the bulkhead connector and convert my amp guage to a volt guage. My question is, why can't I replicate what came on the Dodge service p/u's? The one I owned had heavy guage wires running through the firewall to the amp guage which had brass shunts bridging the guage terminals to prevent overloading the guage. The alternator in my truck was a giant 100amp style and powered a number of "accessories". Never had any problems, I did remove one of the shunts from the stack for a little bit more movement of the guage needle. There are some aftermarket shunts available to mount remotely and run smaller guage wires to the amp guage, and they come in different amp ratings to adjust needle movement. The alternator I will be using is Denso 120amp off Dodge van. Thanks.