NVENC and NVDEC for video streaming over internet

Hi,
We take input in form of UDP://234.234.1.1:1234(multicast) 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

https://developer.nvidia.com/video-encode-decode-gpu-support-matrix
https://developer.nvidia.com/nvidia-video-codec-sdk

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

Regards