There are one or two people in the US that can do the modification but the prices are very high for obvious reasons. As mentioned you have to cut the Tiger receiver off in the rear and weld the SVDS receiver stub in place. This requires an exacting amount of precision because the optic rail is also cut during the process and the SVDS stub portion must also be perfectly aligned with the original rail. The gas system will remain the stock Tiger system because the SVDS barrel has a larger OD than the Tiger and the parts don't fit easily. For the flash hider a shim is welded to make it fit but it was explained to me that the gas system is too finicky to go that route.
Probably the only realistic way to get the parts is to find someone in the UK or Russia who is willing to buy a complete deact rifle then have it cut up and the parts sent over. In particular the SVDS receiver stub has to be cut in a certain place to be sure it will fit the Tiger receiver.
In this day and age the deact rifles seem to be very rare and Russian customs in particular seems to be clamping down on parts leaving the country. Absolutely none of this will be cheap, or quick either so if you decide to commit expect for the project to take a long time, possibly years.
Z