NVENC and NVDEC for video streaming over internet

We take input in form of UDP:// and the video codec of each of streams/channels are SD MPEG 2, SD MPEG 4 and HD (2.64). We need to do transcoding to distribute the channel over Internet/Intranet.
The CPU ( Intel I5,8 core, 2.80 Ghz, 32 GB RAM) gets fully loaded on using even 8 channels of SD MPEG 2 for transcoding, Hence we are looking for using NVIDIA GPU cards to take load of encoding/decodinng as Wowza streaming engine supports NVIDIA cards as per below link


Question 1) Should we go with Nvidia Quadro cards like K6000, P4000, M4000 OR Tesla series of M10,K10,K80,M60(that has 2 GPU), we have to take cost and number of streams that it can encode into account.

To give you some idea, the Kepler GPUs could process around 490fps @ 720p VBR and the first generation Maxwells could process around 820fps while the second generation Maxwell GPU could process around 1100fps with the same settings.

I want to find out how many streams SD MPEG 4 transcode to H.264 codec OR HD MPEG 4 (transrate to 720p) can be handled by K6000(Maxwell 2nd Gen).
Is there any defined formula to find "Number of streams that can be encoded/decoded by any Nvidia card,

As we don’t need multi-monitor displays OR deep learning, but Only video encoding/decoding, which is the ideal GPU card that can help in transcoding maximum streams on a single server

Any help is appreciated as we have to finalize by Monday