Since more than 50% of the partnership interest
was transferred a return is required for the old partnership as of 4/3 as a technical termination has occurred.
"For tax purposes, the termination of a partnership or an LLC
classified as a partnership (collectively referred to here as an LLC) is triggered if there is a sale or exchange of 50% or more of the total interests in the LLC's capital and profits within a 12-month period (Sec. 708(b)(1)(B)). "
As to revaluation, there is generally no tax impact to the partnership or the contributing partner as it is the partnership basis in assets on contribution to the new partnership that is being adjusted.
But the partners that continued in both the old and new partnerships likely could have a tax consequence since the technical termination is treated like a deemed distribution
and the relief of liability
due to the new partner can result in taxable income
for the partners that no longer have such a large share of the partnership liabilities.
" Because a reduction in a partner's share of partnership's liabilities is treated as a distribution of cash, see §752(b), the contribution of cash can be taxable to a continuing partner whose outside basis is insufficient to absorb the constructive distribution, see §731(a)(1)."Regulations
on the basis adjustment
A good plain language explanation of section 754 adjustment is at
Based on the facts given in your question there will be a final return of the old partnership as of 4/3 and a short year return of the new partnership from 4/3 to 6/30 (presuming the new partnership does use a 6/30 fiscal year end).
You will be well advised to engage a tax practitioner with experience in partnership terminations and formations to assist in applying the complex rules
to your particular facts and circumstances.
The links included above (sorry you will have to copy and paste to a browser) can give basic guidance.