I'm approaching this a little bit differently in that I don't have an interest in capping the upside. There is the potential for explosive gains for any calls if the stock heads well north of $420. Even a small squeeze to $500ish would mean huge profits on calls. The uncertainties are whether the deal happens and when it happens. We can make intelligent guesses for both of those uncertainties as well as ensuring if it doesn't go through, or it goes through much later than expected, that we still come out ok.
I'm going off of the premise that call options are going to approach intrinsic value as uncertainty regarding the buyout is reduced. This would also mean the stock would trade pretty close to $420, perhaps 5% or so below, so let's say $400. We don't know how long it will take to increase the certainty this buyout will happen, but based upon Dell as well as the SolarCity buyout, it seems likely that the stock will trade close to the buyout price within 4 months and possibly much sooner. Once a deal is put together and announced, there would still be the uncertainty of the shareholder vote, but knowing Elon, there probably won't be that much uncertainty about the outcome. Therefore, once a deal is announced, I would consider the uncertainty to be very low. I think announcement of an accepted offer dependent only upon shareholder vote is likely to happen within 2 months. This is because I think Tesla will want the shareholder vote to happen ideally before Q3 ER in early November. I think the vote will happen by the end of October or no later than December. I think the deal will be announced at least 6 weeks before the shareholder vote. This would mean that we would know the details of the deal somewhere between early September and early November. After that time, I think the stock will trade at $400+. Also after that time, stock options beyond J19 LEAPs or March at the latest, will lose their time value.
Here are some calls I have looked at. Keep in mind that if the stock runs up fast well before expiration of the calls, they will be much more profitable, but these are worst case valuations assuming the stock trades near $420 by expiration of the call. As you would expect, you are rewarded with a higher profit with the nearer dated calls due to the time risk. If the deal fails, the stock will likely drop, perhaps to $300ish, temporarily. Due to financials improving dramatically by Q4 ER, the best approach would likely be to roll out the options to March OTM.
SEP21 $360
Premium: $21.7
Intrinsic Value: $60
Gain near expiration with stock around $420: 176%
Pretty high risk due to expiration in about 6 weeks.
OCT $360
Premium: $26.7
Intrinsic Value: $60
Gain near expiration with stock around $420: 125%
Moderate risk since these expire in about 10 weeks.
NOV $350
Premium: $39.0
Intrinsic Value: $70
Gain near expiration with stock around $420: 79%
Lower risk since you have about 14 weeks before these expire.
DEC $370
Premium: $31.0
Intrinsic Value: $50
Gain near expiration with stock around $420: 61%
Even lower risk with 18 weeks to expiration.
J19 $350
Premium: $46.0
Intrinsic Value: $70
Gain near expiration with stock around $420: 52%
Lowest risk given about 22 weeks to expiration.