It depends on what the premium is. I don't think I'd go four years given his age + health history, but a high AAV on a 3 year deal would be perfectly reasonable, IMO. Or a vesting option for the 4th year based on health/innings. The other alternative would be to sign multiple middle tier starters who are a solid bet for a 2+ war (Keuchel, Gibson, Porcello types). You get more stability that way and less risk, but less upside/talent as well.
Wheeler would be good too in isolation, but I just see the QO as something Shatkins would not want to mess around with. We are talking about overpaying a free agent, losing a high 2nd round pick (+ the draft pool that comes with it), and $500k in intl money. If the Jays don't feel they are one player away, and are coming off a season where they intentionally tanked, then giving all that up for a rotation upgrade makes little sense. The only exception would be if they signed Cole, which seems highly unlikely.