Would it be terrible idea to get a 5070 GPU to replace my 2070?

I'm mostly wanting AV1 transcoding and it needs to fit in length < 295mm due to case size so I think that rules out the Ti models. Price point is acceptable to me. I am limited to PCIe 3.0 , but I'm not sure thats a big deal for me, if I do a new build at least I will already have a newer GPU that isn't $4000. The 5060 only has x8, so doesn't take advantage of my x16. I figure buy now, prices are only going to go up and extend current build another few years. Motherboard: MSI MPG Z390 GAMING PRO CARBON AC CPU + Cooler: Intel Core i7‑9700K with Noctua NH‑D15 Memory: G.SKILL Ripjaws V 64GB (4×16GB) DDR4‑3200, Model F4‑3200C16D‑32GVK (2 kits) Storage: Samsung 970 EVO Plus 2TB NVMe (MZ‑V7S2T0B/AM) GPU: MSI GeForce RTX 2070 ARMOR 8G PSU: Corsair RM750x (CP‑9020179‑NA) Case: Phanteks Eclipse P600S (PH‑EC600PSTG\_WT01) Case Fans: Phanteks T30‑120 Triple‑Pack